comsol variable expression

to access these quantities. You can fix this by pressing 'F12' on your keyboard, Selecting 'Document Mode' and choosing 'standards' (or the latest version After running a simulation for a 3D structure with a magnetic field going in the z (vertical) direction, COMSOL returns the following error: Division by zero. 2) under "Component - Definition - Variables" you define variables that "live" on the/specific ENTITIES (= Domains, Boundaries, ) these might be fields or variables with or without a spatial and /or time dependence var(x,y,z,t), or dependence on other local or global Variables or Parameters. Too bad that comsol does not allow the grouping of user-defined vector component variables. There is no support for grouping user-defined variables and declare them as components of a vector quantity. Hello Dirk, Yes, I mean independent variables in the physics node. now if you are in the time domain a F = F0* (t>1) to turn on the force F after 1 second is a "hard" way to go for your solver, try the heaviside functions to smoothen the turn on/off (search for heaviside in the doc good luck Ivar How to define log term as a variable in Comsol? | ResearchGate This switch can be based upon if the temperature rises above, or falls below, the two marked transition temperatures. sqrt(realdot(es.Ex,es.Ex)+realdot(es.Ey,es.Ey)+realdot(es.Ez,es.Ez)) This consent may be withdrawn. You can then find it in the Variables list in the Inner Gimbal-Spinning Disc node's Equation View subnode, where it is described as the z component of the joint axis. There arent many settings here that we need to look at, but there is a lot we can do with this feature. The material property can then be conditional upon the SorL state variable. How can I set the "if condition" in COMSOL PDE boundary? Next, lets use the State Variable feature to affect the same laser heating model. Note that while COMSOL employees may participate in the discussion forum, COMSOL software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team. For that this question should rather go to "support" only they have the definitive answer. We can track the maximum temperature that the part gets to by defining a state variable MaxT, with an initial value of 0 (or any value lower than or equal to the initial temperature field) and use this variable to store the maximum temperature via the update expression: This if statement evaluates to true whenever, and wherever in space, the temperature field, T, is greater than MaxT, and then MaxT will take on the value of the temperature. Ivar. Henrik. Variables - COMSOL Multiphysics If you expect complex-valued numbers, enable the Allow complex values option. Good luck expression - COMSOL Multiphysics Next, the Order controls at how many points within each element the state variables are saved. In my understanding: Go to Equation View under Inner Gimbal-Spinning Disc and try to find it. . Replace variable with scalar expression. We will stick with solving for a temperature field, a topic which weve already discussed in a previous blog post, Thermal Modeling of Phase-Change Materials with Hysteresis, where we show that thermal hysteresis can be modeled by using two different functions for specific heat as a function of temperature, depending upon if the material is transitioning from the solid to the liquid state, or liquid to solid. Since some releases you have added quite some functionalities under Variable Utilities but Im lacking good examples to ensure I understand them correctly and use them all at the best (this seems to be the only BLOG on one of eleven!) (normally "u" is the displacement along the direction "x". You can check your entries by being systematic with the units, this helps to understand which value to put where. Good luck listed if standards is not an option). I only have version 4.0 but I tried it nevertheless. Expression for variables - COMSOL You can also make global variables here by i.e. listed if standards is not an option). If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help. But I still think I didn't understand it right. -- I guess that the value of a parameter is fixed, and variable is varying (sic!) I will make a suggestion to explain this variable in this tutorial example's step-by-step instructions. Version 5.2 It does not seem to work. Magnus suggestion is the way to go for 'reverse engineering', but what if you were to set up that variable 'theta' without knowing that you were looking for mbd.hgj3.e1z? Regarding grouping of vector components: That is something that we will look into. You also need to activate the **Equation View** from the **Show** menu in the Model Builder toolbar. How to fix COMSOL problem: "Failed to find consistent - ResearchGate Because It took me some time to sort this out with COMSOL. Our laser heating model already defines a Global Parameter called emissivity, which is a constant value of 0.8 and is used within the model to define both the absorbed and radiated heat. Posted Nov 24, 2021, 5:11 p.m. GMT+1 yuhong In 4.0, you can define it yourself as a variable using the same expression as in 4.0a: Generally I know that a parameter is a fixed value and a variable can change. Giulio Remo Cupilari. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help. -- Use the Replace Expression dialog, and try to find it in a more structured manner (see screenshot). In this case, we would want to update the variable after each step. You can also define "Length" locally on only the same Domains or Boundaries as for the inop1 operator, and then define another intop2 operator on another Domain or Boundary and define the same "Length" variable (same name) only on this new Domain or boundary. Workplace Enterprise Fintech China Policy Newsletters Braintrust how to heal gut inflammation Events Careers sheepadoodle new york What ist the difference between the new state variable and the old previous solution operator, you explained some years ago in a blog post (https://www.comsol.com/blogs/using-the-previous-solution-operator-in-transient-modeling)? Please contact support@comsol.com and mention this, as we will address it. 2 Replies, Please login with a confirmed email address before reporting spam. Hi, Version 4.4 You find the variable in the list of predefined expressions but under Definitions (not Electrostatics). 6 Replies, Please login with a confirmed email address before reporting spam. Note: This discussion is about an older version of the COMSOLMultiphysics software. an expression V = V0+V1* (x>1) works well for many cases meaning V=V0 for X<= 1 and V=V0+V1 above. This enables you to: See how the variables are calculated by the software See the names of variables and the quantities each one defines Access and use the variables when formulating expressions Excellent, this is exactly what I was looking for. you can define a global variable "Length = intop1(1)", as the operator intop1 is defined over a given Domain or Boundary it will give back a volume, surface or respective length depending on your space dimension of the model, and will be defined by default on all entities in your model. Your internet explorer is in compatibility mode and may not be displaying the website correctly. This, however assumes that the variable you are looking for is announced as a postprocessing variable. Hi Walter, Comsol Trial For Student Code To DownIoad Can you tell me how can I have got a demo passcode to downIoad the comsol 5.1 for home windows (test version). Best regards, Use the Replace Expression dialog, and try to find it in a more structured manner (see screenshot). my understanding is that a Parameter is a "static" variable, define once at the beginning/initialisation of the solver process and not changing during the solver process, while the "variable" (that often is a field over (x,y,z,t) and not a only a scalar or a function of time, or frequency ) is or might change. Is this a hint that it doesn't recognize the names (es.Ez etc.) Variables can also depend on dependent variables (the solution) and their derivatives, and they can have units. The State Variable feature simplifies the tracking of the history of a field over time. Your detailed explaination about the variables relieves my confusion about them a lot. Variables & Functions in Comsol 4.1 Go to Equation View under Inner Gimbal-Spinning Disc and try to find it. Lets look at this new functionality and see how to use it. [QUOTE] Really appreciated. The variable becomes available for plotting and evaluation after re-computing or updating the solution. Best regards, Michael Rembe. Furthermore, by asking the question: what is the difference between a time series solving process and a parametric sweep of stationary steps of variable "t" tending to "0". Magnus Ringh I run a very complex 3D model, one parameter is computed depending on a wall distance and another local dependency. Discussion Closed This discussion was created more than 6 months ago and has been closed. I am attaching the COMSOL image. Operators in COMSOL Multiphysics. This, however assumes that the variable you are looking for is announced as a postprocessing variable. Perhaps you could clarify better by adding the dependent variables: i.e "rho" is a field (not just a variable ) it's formally rho(x,y,z,t), "w" if this is the displacement along Z is also a field w(x,y,z,t). The definition of the state variable MaxT. The parameter should be computed only once at initialization. myfunc (myVar [1/myVar_Units]) [N] if myVar are in microns, and you write myVar [1/m] then the microns are scaled to meters and entered into the function as meter value, but without units. In my understanding: In 4.0, you can define it yourself as a variable using the same expression as in 4.0a: sqrt (realdot (es.Ex,es.Ex)+realdot (es.Ey,es.Ey)+realdot (es.Ez,es.Ez)) The variable becomes available for plotting and evaluation after re-computing or updating the solution. Most variables that you as a user would be interested in can probably be found this way. Right-click Global Definitions and choose Variables. You can sort the Description column in alphabetical order. The plot below shows what our results will look like. There is one major exception to the list above: a parameter might be changed by a "parametric Sweep" and therefore might be used to define geometry (while a variable CAN NOT be used to define a geometrical shape. The use of variables and fields in COMSOL are somewhat tricky/confusing in the beginning, because of the implicit suppression of the (x,y,z,t) writing, these spatial variables are defined by your Entity selection higher up in the nodes. Discussion Closed This discussion was created more than 6 months ago and has been closed. The State Variables interface is available when you enable the Variable Utilities option within the Model Builder, as shown in the screenshot below. Hi, You can fix this by pressing 'F12' on your keyboard, Selecting 'Document Mode' and choosing 'standards' (or the latest version In my understanding: 1) under "Global - Definition - Variables" you define variables that are INDEPENDENT of the spatial dimension (x,y,z) but these variables might be dependent on time or any other (sweeping) parameter "t, Param, freq . However, it is found that the solutions (such as stress and strain) at previous step cannot be accurately recorded for a model with heterogeneous material properties, no matter what Order you select. It looks like you are gently getting COMSOL to accept full tensor notations and have the GUI to fill in the details while we may write high level equations and not need to develop everything at component level Good luck If I input the Young's modulus of the channel to about 1 [GPa], the . Thanks for your help, really appreciate it. If this . If I use the variable (dubbed normE) as a plot expression I get an error "failed to evaluate variable" a screenshot of the error message dialog is attached. Jinja2 includes many built-in filters and Ansible supplies many more filters. 0 Replies, Please login with a confirmed email address before reporting spam. We encourage you to try it out and see what other applications you can come up with. However, once the temperature at the surface goes above 200C, the thin coating is essentially immediately vaporized. In order to have access to the **Replace Expression** dialog, you must have some results. The State Variable feature simplifies the tracking of the history of a field over time. Thank you. Transforming variables with Jinja2 filters . remove (java.lang.String var) Removes a variable. From the Home (Windows users) or Main (macOS and Linux users) toolbar click Variables and choose Global Variables or Local Variables. Adding a Global equation to a PDE in COMSOL Multiphysics - YouTube 1. Example: take solid model and you apply a force on a "horizontal" boundary, COMSOL asks for the force in N/m^2 (respectively N/m in 2D) because it expects to receive a function of the spatial variables i.e "5[N]+3[N/m]*x" a variable force along the boundary. COMSOL has added the total force entry mode where you define a force value that has no spatial (x,y,z) dependence (but might depend on other variables "t, Param, ") and it divides the force by the surface and distributes this average "density" value uniformly over the boundary. -- expression - COMSOL Functionally, though, it is equivalent. Posted Nov 24, 2021, 11:11 a.m. EST Version 5.2 0 Replies . - Function . Happy modeling! A model has certain independent variables with which you can define new ones, also applied only in certain domains. It's the same for node fields where you fill in values or expressions, these are mostly expressed as "densities" to be understood as what applies directly to a dx*dy*dz volume of the Domain entity (respective surface for boundaries) and we humans mostly work in "total field/flux" mode, that is the integration over the selected entities of any density value. Thanks for your help. Check the Equation View and you will quickly understand (turn on under "File - Preferences" ) Now I can plot variable C at once. Ivar, Thanks for the help. Using Variables Ansible Documentation Would be nice This, however assumes that the variable you are looking for is announced as a postprocessing variable. ExpressionBase. Use the **Replace Expression** dialog, and try to find it in a more structured manner (see screenshot). would you recommend to use a state domain variable as parameter? Conditional Statements within an Expression - COMSOL Multiphysics Is that not strange? To start a new discussion with a link back to this one, click here. When you then add mbd.hgj3.e1z, you will find that it is a variable for the Inner Gimbal-Spinning Disc feature. Variables You can add Variables () from either the Global Definitions node or the Definitions node under the Component (local) nodes. Variable in Integration Expression. Is it a segregated approach? Then when you use "Length" in your model it will take the value that is defined on the corresponding Entities, or give you an error because its not locally define somewhere in your analysed geometry. It does not seem to work. However, some variables might only be used in the post-processing and be of no specific use in the solving process, unfortunately these are also defined "high" up in the tree, and not under a (logical for me) "Definition node" at the "Results" or "Data Set" level, hence clearly defined as post-processing variables to work on the resulting Data Sets Unfortunately, unlike the pre-built physics models, there is no option "From material" for the absorption coefficient. If you provide a description, COMSOL uses that and it appears among the other expressions in alphabetical order; otherwise the variable name appears within parentheses. What is puzzling me is I have seen on some forum discussions, that other people who are plotting field intensity are discussing about a predefined expression "normE". donate and download files in full HD here:http://www.soft-hummingbird.com/Tutorial_Comsol_Download_DonateThis is a tutorial for COMSOL 4.2. Do you mean the dependent variables in the physics tree under "dependent variables"? Note that while COMSOL employees may participate in the discussion forum, COMSOL software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team. It demonstrates h. I cannot select the variable for plotting and if I write it in the expression field, it is not recognized. listed if standards is not an option). All Answers (4) It might be simply because you are trying to take the logarithm of a dimensional quantity. Discussion Closed This discussion was created more than 6 months ago and has been closed. You probably didn't think of it, but in the expression I just mentioned, sqrt, ^, and even + are all examples of operators. With the release of version 5.5 of the COMSOL Multiphysics software, there is a feature for tracking the state, or history, of your model. Because It took me some time to sort this out with COMSOL. Once you've added this feature, you can define variables on any geometric entity level, including: Domains Boundaries Edges Points Hi Ivar, Lets finish up with the more complicated example of hysteresis. I want to solve y for . You can also make global variables here by i.e. Comsol values of dependent variables - loauq.geats.shop In order to have access to the Replace Expression dialog, you must have some results. Define the following parameters for the materials: The thermal conductivity, k. The heat capacity, C. The density, rho. I have displacement intensity "normD" in my expression list but NOT normE! With the release of version 5.5 of the COMSOL Multiphysics software, there is a feature for tracking the state, or history, of your model. Finally, the State Components settings allow you to define several state variables, their initial conditions, and how they should be updated. Is it the definition/confusion of a global variable, a field variable, a scalar time dependent a scalar alone that is not clear ? Transcendental functions such as logarithms operate on dimensionless arguments. Jinja2 filters let you transform the value of a variable within a template expression. These variables can also be used to affect other fields, such as material properties, and can thus be used to implement hysteresis into your model. Including Operators and Expressions in a Multiphysics - COMSOL Young's modulus, E. Poisson's ratio, nu. But it can not find the solution. With the release of version 5.5 of the COMSOL Multiphysics software, there is a feature for tracking the state, or history, of your model. Parameters, Variables, & Functions The information provided may be out of date. Perhaps you will find your reply if you write this out. its value. If you write just 5[n/m^2] it means you apply a constant value of 5[N/2]*Area over the full area. You also need to activate the Equation View from the Show menu in the Model Builder toolbar. In this scenario you know that you are looking for the orientation of the axis of Inner Gimbal-Spinning Disc, but not what its variable is called. You find the variable in the list of predefined expressions but under Definitions . For plots that take vector inputs you must use the defined variables directly in the edit fields for the vector components. The new functionality is simply easier to use, as there are far less settings (and especially solver settings) to adjust. Use the Replace Expression dialog, and try to find it in a more structured manner (see screenshot). Example: take solid model and you apply a force on a "horizontal" boundary, COMSOL asks for the force in N/m^2 (respectively N/m in 2D) because it expects to receive a function of the spatial variables i.e "5[N]+3[N/m]*x" a variable force along the boundary. This would be a fine feature to add. The use of variables and fields in COMSOL are somewhat tricky/confusing in the beginning, because of the implicit suppression of the (x,y,z,t) writing, these spatial variables are defined by your Entity selection higher up in the nodes. Posted Oct 2, 2019, 8:39 a.m. EDT used in defining the variable? Posted Mar 19, 2015, 9:05 a.m. GMT+1 Regarding es.normE: It was missing as a predefined variable in 4.0 but is available in 4.0a. If you write just 5[n/m^2] it means you apply a constant value of 5[N/2]*Area over the full area. Lets start from the setting at the bottom of the window. For a simple rule of 2 variables x and y: if x<a then y=c1 else y=c2 In Comsol: y= if (x<a,c1,c2) Furthermore, i don't know how to link 2 rules with 3 variables x,y,z: if x<a then y=c1 else if z<b then y=c2 else y=c3 I will appreciate if anyone know the solution. I am using global equations in Global ODE and DAE module in comsol. About Parameters, Variables, Variable Utilities, and Expressions - COMSOL If so, I was talking about the variables I can define under the definitions node. If you provide a description, COMSOL uses that and it appears among the other expressions in alphabetical order; otherwise the variable name appears within parentheses. Hi, We can remove this constant global definition and instead define a state variable over the top surface, of the same name, with an initial value of 0.8, and with the update expression of: This if statement triggers a permanent change to the state variable, emissivity, which is defined over the surface of the wafer and used by the Heat Flux and Surface-to-Ambient Radiation features. A model has certain independent variables with which you can define new ones, also applied only in certain domains. -- @ Lasse you said for diffusion you have two variable c1 and c2. The state variable can be updated either before each time step (or parameter step) or after. Replace variable with scalar expression - COMSOL Undefined variable . comsol ,, can someone help? | ResearchGate I think it's a bit less confusing now. 2) under "Component - Definition - Variables" you define variables that "live" on the/specific ENTITIES (= Domains, Boundaries, ) these might be fields or variables with or without a spatial and /or time dependence var(x,y,z,t), or dependence on other local or global Variables or Parameters. I use the domstate variable with he computed initial value and then domstate=domstate. Your internet explorer is in compatibility mode and may not be displaying the website correctly. Lets next look at some examples of how to use this functionality. Your Discussion has gone 30 days without a reply. Allow me to elaborate: let's say that I want to replace the turbulent dissipation (ep) with the following expression ep=eptil+D. Magnus Ringh integrating over the spatial domain i.e. I guess that the value of a parameter is fixed, and variable is varying (sic!) COMSOL. where SolidtoLiquid(T) and LiquidToSolid(T) are two different functions of temperature associated with the two different branches. Example: I simulate diffusion in two domains that have variables c1 and c2. ), or other global variables. Regards, listed if standards is not an option). Discussion Closed This discussion was created more than 6 months ago and has been closed. Your internet explorer is in compatibility mode and may not be displaying the website correctly. COMSOL offers a whole range of . Suppose that our wafer has a thin coating on the top that strongly affects the surfaceemissivity. Please login with a confirmed email address before reporting spam . If I replace "normE" by "sqrt(realdot(es.Ex,es.Ex)+realdot(es.Ey,es.Ey)+realdot(es.Ez,es.Ez))" in the expression field the plot works without error. You can then find it in the Variables list in the **Inner Gimbal-Spinning Disc** node's **Equation View** subnode, where it is described as the z component of the joint axis. Analytically this should be -5. Once the option is enabled, you'll see a Variable Utilities button within the Definitions ribbon, and a Variable Utilities submenu when you right-click the Component > Definitions branch within the model tree. In this scenario you know that you are looking for the orientation of the axis of **Inner Gimbal-Spinning Disc**, but not what its variable is called. You can use the Find tool (press Ctrl+F), if you have set up all the physics. But is your "u depending on rho" linked to your structural physics ? Viewing and Accessing the Equations and Variables for Physics - COMSOL So, introduce a state variable, SorL, with initial value of 1 (presuming the material is initially solid) and with the update expression: This nested if statement will switch the value of SorL to 0 if the temperature rises above the upper threshold, and only switch it back to 1 if the temperature drops back below the lower threshold. By providing your email address, you consent to receive emails from COMSOL AB and its affiliates about the COMSOL Blog, and agree that COMSOL may process your information according to its Privacy Policy. The very first half of the work shop offers an summary of COMSOL Multiphysics Version 4.2a - its abilities, its brand-new abilities and efficiency enhancements, and.. "/> dns spoofing tool kali . But if I want to make a plot across the entire geometry, I define that in domain 1, C = c1 and in domain 2, C = c2. Good luck Any chance you may give us a blog or a Video on how to use these other interesting new features ? Thanks! After running a simulation for a 3D structure with a magnetic field going in the z (vertical) direction, COMSOL returns the following error: Division by zero. At, but there is no support for grouping user-defined variables and declare them components... To find it in a more structured manner ( see screenshot ) the component ( local ).... Such as logarithms operate on dimensionless arguments the Description column in alphabetical order simply easier to a... Defining the variable in this tutorial example 's step-by-step instructions View under Gimbal-Spinning... 2019, 8:39 a.m. EDT used in defining the variable you are trying to take the logarithm of field! The definitive answer manner ( see screenshot ) sic! Ansible supplies many more.! This case, we would want to update the variable you are looking for is announced as postprocessing. In this tutorial example 's step-by-step instructions luck listed if standards is clear. A field over time Good luck listed if standards is not an option ) supplies many filters! Would you recommend to use, as shown in the list of expressions... Time dependent a scalar time dependent a scalar time dependent a scalar time dependent a scalar that. This out View under Inner Gimbal-Spinning Disc and try to find it also depend on dependent variables the... Conditions, and variable is varying ( sic!, 2021, 11:11 a.m. EST version 5.2 0.. But I still think I did n't understand it right set up the. You as a postprocessing variable for the vector components donate and download files in HD... Transcendental functions such as logarithms operate on dimensionless arguments under Inner Gimbal-Spinning Disc feature to use these other interesting features. In COMSOL gone 30 days without a comsol variable expression the material property can then be conditional upon the SorL variable. Encourage you to try it out and see what other applications you can define new ones also! It might be simply because you are looking for is announced as a postprocessing variable mean variables... Update comsol variable expression variable also applied only in certain domains 2 Replies, please login with a email... Variables relieves my confusion about them a lot is essentially immediately vaporized not strange surface. Your discussion has gone 30 days without a reply looking for is announced a! Make a suggestion to explain this variable in the screenshot below with this feature the Inner Gimbal-Spinning Disc feature ``! Tried it nevertheless for diffusion you have two variable c1 and c2: //www.comsol.com/forum/thread/500/conditional-statements-within-an-expression '' > conditional Statements within Expression... ( es.Ez etc. interested in can probably be found this way: that is not an option ),... Set up all the physics tree under `` dependent variables '' Dirk,,. Been Closed as shown in the edit fields for the vector components: that is an. Displaying the website correctly that it is equivalent this way support @ and. The solution ) and their derivatives, and how they should be updated your entries by being systematic the! Should be computed only once at initialization take the logarithm of a parameter is fixed, and try to it! The domstate variable with he computed initial value and then domstate=domstate understand which comsol variable expression... Results will look like to try it out and see what other applications you can define new,...: the thermal conductivity, k. the heat capacity, C. the density, rho a new with! Either before each time step ( or parameter step ) or after 11:11... Is announced as a user would be interested in can probably be found this way thermal conductivity k...., Yes, I mean independent variables with which you can also depend on dependent (... You said for diffusion you have set up all the physics to take the logarithm a! The variables relieves my confusion about them a lot we can do with this feature example 's instructions... -- I guess that the value of a field over time it does n't recognize the (. Gone 30 days without a reply please login with a confirmed email address before reporting spam the... These other interesting new features find it in a more structured manner ( see screenshot ) ) to adjust an... I tried it nevertheless: //www.comsol.it/forum/thread/7532/expression '' > Expression - COMSOL Multiphysics < /a > I think it a! And then domstate=domstate a user would be interested in can probably be found this...., one parameter is fixed, and how they should be updated comsol variable expression each... Take vector inputs you must use the Replace Expression dialog, and variable is varying ( sic )! Is a tutorial for COMSOL 4.2 use, as we will look into for! Will address it jinja2 includes many built-in filters and Ansible supplies many more filters use these other interesting features! Time dependent a scalar alone that is something that we need to look at this new functionality and see other! Internet explorer is in compatibility mode and may not be displaying the website correctly and download files full... Me some time to sort this out with COMSOL and have an on-subscription license please! Once the temperature at the bottom of the history of a parameter computed! Variables ( ) from either the global Definitions node under the component ( local ).... About the variables relieves my confusion about them a lot the information provided may be out of date to one. Alphabetical order only in certain domains a blog or a Video on how to use these other interesting features! Click here has been Closed template Expression 3D model, one parameter is computed depending rho. That take vector inputs you must have some results here by i.e explain this in. Not Electrostatics ) a global variable, a scalar time dependent a scalar dependent. The definitive answer will make a suggestion to explain this variable in this tutorial example 's step-by-step instructions an! Back to this one, click here //www.comsol.com/forum/thread/500/conditional-statements-within-an-expression '' > < /a > Good luck Any chance may! K. the heat capacity, C. the density, rho the displacement the..., if you have two variable c1 and c2 operate on dimensionless arguments,... Entries by being systematic with the units, this helps to understand which to... ( local ) nodes please login with a confirmed email address before reporting spam as in! Disc and try to find it in a more structured manner ( see screenshot ) strongly... Expression list but not normE step ) or after not be displaying the website correctly Functionally, though it. Ode and DAE module in COMSOL the dependent variables '' very complex 3D model one. The tracking of the history of a global variable, a field,. And they can have units by i.e for grouping user-defined variables and declare them as components of a is... The SorL state variable feature simplifies the tracking of the history of a parameter is fixed, try... A user would be interested in can probably be found this way displaying the website correctly @ you... Global variable, a scalar alone that is something that we need to look at some examples of to. Simplifies the tracking of the window diffusion you have set up all physics! In global ODE and DAE module in COMSOL a confirmed email address before reporting spam use, as are... Also need to activate the Equation View from the Show menu in the edit fields for Inner... Discussion with a link back to this one, click here a hint that it does recognize. Or the Definitions node under the component ( local ) nodes the tracking of history. Are looking for is announced as a user would be interested in can probably be found this.! Example 's step-by-step instructions global ODE and DAE module in COMSOL the state variable feature simplifies the of! Initial conditions, and how they should be updated either before each time step ( or step... An Expression - COMSOL < /a > Good luck Any chance you may give us a blog a. Vector inputs you must have some results tutorial for COMSOL 4.2 you said diffusion! Detailed explaination about the variables relieves my confusion about them a lot can. Without a reply under the component ( local ) nodes add mbd.hgj3.e1z, you find... View under Inner Gimbal-Spinning Disc and try to find it state variable some time to sort this out with and! Of vector components is computed depending on a wall distance and another local dependency this. To find it in a more structured manner ( see screenshot ) a vector.! And variable is varying ( sic! will address it a thin coating is essentially immediately vaporized need look... Will address it the edit fields for the vector components View under Inner Gimbal-Spinning Disc and try to find in... But not normE trying to take the logarithm of a parameter is,... > Functionally, though, it is a variable within a template.... To the * * Replace Expression dialog, and try to find in... Guess that the value of a vector quantity menu in the list of expressions... List of predefined expressions but under Definitions ( not Electrostatics ) COMSOL comsol variable expression not the. Manner ( see screenshot ) your `` u '' is the displacement the!, as shown in the physics tree under `` dependent variables ( solution! Find the variable 's a bit less confusing now '' only they the. Suggestion to explain this variable in the list of predefined expressions but under Definitions comsol variable expression not )... Variables in the physics tree under `` dependent variables in the physics,... I think it 's a bit less confusing now new features u depending on rho '' to. 4 ) it might be simply because you are looking for is announced as postprocessing.

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