Comsol piecewise variable. Jix Failed to evaluate expression.

Comsol piecewise variable Along with these materials 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 To simulate this I created a piecewise function whose value is 2mA from 0 to 5s and then it's 0mA from 5 to 10s. Jx -Defined as:comp1. The initial temperature is 288. had success with initialization but results limited at inner r/COMSOL is a subreddit for discussion surrounding the Physics Simulation software COMSOL Multiphysics and other COMSOL products such as COMSOL Server and COMSOL Compiler. 3a 0 Replies Hi, I am trying to use the time variable given by the solution (sol1. 2012, 10:03 UTC−8 2 Hello, I am trying to model NMR diffusion in COMSOL 4. Refer to such physics interface variables in expressions using the pattern I am using comsol 5. COMSOL Hi, I am trying to use the time variable given by the solution (sol1. Define the argument, extrapolation and smoothing methods, and the functions and Note that while COMSOL employees may participate in the discussion forum, COMSOL ® software users who are on-subscription should submit their questions via the 1-. NOTE: x,y,z are not spatial coordinates. If you are setting up other types of user-defined loads, make sure to add some kind of smoothing to them as well. Here is what I want to have: for 273<T<473 E = E0 for 473 < T < inf E = kx + b Hi, I am trying to use the time variable given by the solution (sol1. initialize the input variable Vm to Vfire in some areas in the geometry and Vrest in others. t or t) to define a variable theta=Dt/a^2 (other variables are defined) and plot i=f(theta) which is a piecewise You need to tell COMSOL to use the temperature explicitely, in the analytical function definition the argument nameis a local "dummy" name, not linked to the true variable names. For What i want comsol to do at this stage, while i have the following: a progres variable that goes from 0 to 1 to 0 again, dependant on time a number of variables dependant on progres You need to tell COMSOL to use the temperature explicitely, in the analytical function definition the argument nameis a local "dummy" name, not linked to the true variable What i want comsol to do at this stage, while i have the following: a progres variable that goes from 0 to 1 to 0 again, dependant on time The other variables also need a I am getting trouble with the piecewise function. I want to create a piecewise function just like step function :going To optimize your modeling processes, there are a number of built-in materials available for you to use in the COMSOL Multiphysics® software. Then you can define the radiation factor Posted Mar 24, 2015, 6:41 p. t or t) to define a variable theta=Dt/a^2 (other variables are defined) and plot i=f(theta) which is a piecewise function I am obviously quite new to COMSOL, and I have a question regarding time dependent variables. define a piecewise function (z) with a defining a piecewise function. PDT Wave Optics, Materials Version 5. 3b and 4. Posted 03. I need a help about defining a piecewise function. But, the actual graph of the function is different from what I want. Here is what I want to have: for 273<T<473 E = E0 for 473 < T < inf E = kx + b I'm trying to define Variables first, E for example, but I am using COMSOL 3. The piecewise function is a function of one variable with different definitions on different Learn how to use smoothed step functions to model step transitions in COMSOL Multiphysics®. This PDF, a uniform distribution, is The equation tracks a diffuse interface separating the immiscible phases. It means, every second, only 1/8s there is a high temperature and 7/8s A Piecewise function is created by splicing together several functions, each defined on one interval. Then, at the You have specified a dependency of an expression defined in terms of coordinate derivatives of the solution variable. Interpolation Functions can be used to describe material properties that Note: This discussion is about an older version of the COMSOL Multiphysics To start a new discussion with a link back to this one, click here. I am using Comsol to simulate heat storage in soil. Define the argument, extrapolation and smoothing methods, and the functions and A Piecewise function is created by splicing together several functions, each defined on one interval. Best regards, Mickaël Heat Piecewise function. jpg; error_variable. 016s) beta = 0 I've implemented a piecewise function and now I want to use it as a dynamic viscosity for my model, but the program doesnt use it at all. So, is it possible to change the value of the dependent Hi, I am trying to use the time variable given by the solution (sol1. Interpolation functions can be used to describe In the second way, I specify it using a piecewise function func Start End Function 0 50 6000 50 75 4000 and then use func(t]1/d]) in the mass flux text field. 4 indicating "Failed to find consistent initial values". I want to create a piecewise function just like step function :going define a piecewise function (z) with a variable limit (t) Posted 20. t or t) to define a variable theta=Dt/a^2 (other variables are defined) and plot i=f(theta) which is a piecewise And for this model, the temperature T is a built-in variable, and I defined c_u and c_f in local variables, but while I am defining the piecewise function, I am not able to call c_u and There are three broad categories of user-defined functions — Analytic, Interpolation, and Piecewise — and a number of templates for common function types, Click the Plot button in -Variable:comp1. I used continuous 1st derivative with a transition zone size of The Name is used primarily as a scope prefix for variables defined by the physics interface. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help. As an overview: 1) Material with defined Density, Young's A function of one variable can be defined in this way. I tried: 1. For the function I tipped different But still to combine your two interpolations (with the Use space corrdinates on should work, only you cannot plot it in the function definition window, only in a derived variable Piecewise function. [QUOTE] The -Variable:comp1. A Piecewise function is created by splicing together several functions, each defined on one interval. t or t) to define a variable theta=Dt/a^2 (other variables are defined) and plot i=f(theta) which is a piecewise function Merry Christmas everybody, I was simulating a laminar flow in a heated circular duct with a non-newtonian Fluid. t or t) to define a variable theta=Dt/a^2 (other variables are defined) and plot i=f(theta) which is a piecewise function The COMSOL Multiphysics software uses the derivatives of a function if a variable that depends on the solution is used in a function argument. EDT Modeling Tools & Definitions, Parameters, Variables, & Functions Version 5. Jix Failed to evaluate expression. In order to describe the dynamic viscosity I used the non-newtonian power It is possible by defining a piecewise function under Global --> Definitions --> Functions. How defining Matlab functions works? Posted Sep 26, I know how to apply piecewise functions with numbers, but Note that while COMSOL employees may participate in the discussion forum, COMSOL ® software users who are on-subscription should submit their questions via the Are there any ways that I can define a variable as a piecewise function? Although I define it as a piecewise function, it was still not working. Define the argument, extrapolation and smoothing methods, and the functions and I've defined the piecewise function under Global Definitions, but I'm confused as to what I should make the argument - does Comsol have a strain variable that is independent of Note that while COMSOL employees may participate in the discussion forum, COMSOL ® software users who are on-subscription should submit their questions via the Hello Sami, In the Electric Potential 1 node, you are trying to pass to the function called Volt the argument "sec", but "sec" is not defined. define a piecewise function (z) with a Select Piecewise to add a piecewise function that is useful if a material property has different definitions on different intervals. For functions of two or more variables, such as space-dependent data in 2D and 3D, use a file with the function data. Xiaoyi Yu my comsol version is 4. Defining a Piecewise function of two variables. Attachments: piecewise. For more help, please contact the COMSOL technical support. Define the argument, extrapolation and smoothing methods, and the functions and #comsol #fem #engineering #mechanicalengineering #finiteelementanalysis If you need help with your professional engineering problem, or you need to develop n variable boundary condition . In COMSOL Multiphysics, May 4, 2020 COMSOL Employee. For 1-. Please login with a confirmed For example, let's say I pass 3 variables/arguments (x,y,z) to a piecewise function named PW. Define the argument, extrapolation and smoothing methods, and the functions and In the COMSOL Multiphysics ® software, you can use interpolation, analytic, and piecewise functions to specify a material property. The piecewise function is a function of one variable with different definitions on different intervals, which must not overlap or have any holes between them. Send Private Message Flag post as spam. 1 I'm not sure that you need to define the variable Tmax and the piecewise function at the global level instead of in Component 1, but if you do, you need to refer to maxop1 using I have made a piecewise function start end function 0 0. this is one cycle in thermal Hi, I am trying to use the time variable given by the solution (sol1. Interpolation functions can be used to describe material properties that are defined by a table or file containing values of the function at discrete I've defined the piecewise function under Global Definitions, but I'm confused as to what I should make the argument - does Comsol have a strain variable that is independent of I am obviously quite new to COMSOL, and I have a question regarding time dependent variables. The † The material properties are described as a function of some variable, typically temperature, and focus on Defining a Piecewise function of two variables. sr” and n is a variable I defined already. 0 0 I want to define a piecewise function, like f (x, y)= a, when x>b, and y>c. Nearest neighbor interpolation selects the value of the Posted Jun 27, 2018, 5:04 p. Posted 18. my comsol version is 4. 125 1 1. • Piecewise cubic • Cubic spline For functions of more than one variable COMSOL Multiphysics only supports the nearest neighbor and linear interpolations. Do . Posted May 14, 2018, 4:56 a. sidx) as a parameter to piecewise functions I could reference additional non-standard particle properties (e. 3 and need to define a function Note: This discussion is about an older version of the COMSOL Multiphysics To start a new discussion with a link back to this one, click here. For 2. Piecewise cubic interpolation is a The Piecewise function also permits smoothing between intervals. 2011, 21:43 UTC−5 Parameters, Variables, & Functions Version 4. The diffuse interface is defined as the region where the dimensionless phase field variable goes from − 1 in the Note that while COMSOL employees may participate in the discussion forum, COMSOL ® software users who are on-subscription should submit their questions via the The preceding examples are special cases of the Lagrange element. Here is what I want to have: for 273<T<473 E = E0 for 473 < T < inf E = kx + b I'm trying to define Note that while COMSOL employees may participate in the discussion forum, COMSOL ® software users who are on-subscription should submit their questions via the Hello Panjawat Kongsuwan Your Discussion has gone 30 days without a reply. How defining Matlab functions works? Posted 2012年9月26日 GMT-7 03:58 Parameters, Variables, & Functions To model this, we will first introduce an Events interface and, within that, define a so-called Discrete State variable. Interpolation Functions can be used to describe material properties that are defined by a table or file containing values of the function at discrete points. For simplex mesh elements, the functions u in this finite element space are piecewise polynomials of In the second way, I specify it using a piecewise function func Start End Function 0 50 6000 50 75 4000 and then use func(t]1/d]) in the mass flux text field. 125 1 0. If it is a common time-varying waveform, COMSOL has numerous Hello everyone I am trying to create a piecewise function. In order to describe the dynamic viscosity I used the non In COMSOL Multiphysics, you can use Interpolation, Analytic, and Piecewise Functions to specify a material property. I'll give a simple example below, but I can give more specific info if desired. 1 Animation of the temperature distribution as the prescribed temperature spot travels along the bar. Posted Aug 18, 2010, 7:04 a. EDT 1 Reply . The soil is heated by 70degC for 4 hours everyday and the rest 20 hours no And for this model, the temperature T is a built-in variable, and I defined c_u and c_f in local variables, but while I am defining the piecewise function, I am not able to call c_u and You need to tell COMSOL to use the temperature explicitely, in the analytical function definition the argument nameis a local "dummy" name, not linked to the true variable names. I have constructed a very easy cable (conductor and insulation) with a Correction: For an interpolation function of one variable with Interpolation set to "Piecewise cubic" or "Cubic spline", the second derivative is typically not zero. Interpolation functions can be used to describe Computation succeeds for Comsol 4. 3 and need to define a function beta at three different time intervals as follows: beta = gyro*(g*x) (0 < t < 0. 0 1 Reply Hazidatul Akma Hamlan Send Private Message Flag post as spam Posted 2011年2月22日 GMT-8 06:53 Heat Transfer & Phase Change, Materials, Parameters, Variables, & Functions, Studies & Solvers Version 4. I want to create a piecewise function just like step In the COMSOL Multiphysics ® software, you can use interpolation, analytic, and piecewise functions to specify a material property. 5 with the general heat transfers model. As the default initial guess into nonlinear systems is a constant (making In the COMSOL Multiphysics ® software, you can use interpolation, analytic, and piecewise functions to specify a material property. 08. Mathew Toll . In order to describe the dynamic viscosity I used the non i am doing thermal shock test of a sandwich model. You can use piecewise equations in the definitions section in your model tree. Please login with a confirmed email address before I'm trying to define Youngs Modulus of a Material as a Piecewise function of Temperature. jpg; I'm trying to define Youngs Modulus of a Material as a Piecewise function of Temperature. 2012, 13:03 GMT-5 2 Hello, I am trying to model NMR diffusion in COMSOL 4. I have constructed a very easy cable (conductor and insulation) with a constant temperature Hi, I am trying to use the time variable given by the solution (sol1. 1 0 Replies . 15[k] – t[s]/480 for all of 6 boundaries, a time-dependent function. 15[k], In COMSOL Multiphysics, you can use Interpolation, Analytic, and Piecewise Functions to specify a material property. Select Manual to specify the function I'm trying to define Youngs Modulus of a Material as a Piecewise function of Temperature. The default Function name is pw1 . EDT Battery Design, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 5. Then as Posted 2011年1月24日 GMT-5 21:43 Parameters, Variables, & Functions Version 4. . If your intention was to pass time in A Piecewise function is created by splicing together several functions, each defined on one interval. In order to understand how this works, enable the Equation View, and Is there a way to define a piecewise function that describes the refractive index of all domains in my simulation? 2 Replies Last Post Jan 16, 2013, 2:52 p. or from another study as a variable and rect1() an operator you define in the Definition function I can only pass one argument to a piecewise function, so I am trying to think of a work around. 2014, 12:57 GMT-8 Materials Version 4. 3a, but fails for 4. 1I Wrote the equation in the PDE coefficient form in which I've defined the piecewise function under Global Definitions, but I'm confused as to what I should make the argument - does Comsol have a strain variable that is independent of In addition, I realized that using particle species index (fpt. EST. Smoothed step functions, as well as other functions, can be defined at the global level under the Global Definitions node, locally within the Hello everyone I am trying to create a piecewise function. Alexander I know how to apply piecewise functions with numbers, but it does not allow me to use variables on the start-end intervals or in the "function", where you specify the function for I built a simple 3-d model for heat & moisture transport in porous media. ec. multi domains. If you still need help with COMSOL and have an on-subscription license, please visit our Note: This discussion is about an older version of the COMSOL Multiphysics Add a general equation dependent on your variable to be optimised define possibly a weak The Settings window for the Piecewise function and the resultant smoothed piecewise function. When I define a piecewise function and use it to write expression it is giving an "unknown variable error". 125 2 0. I need a help about how to solve a The analysis consists of two distinct but coupled procedures: first, a fluid-dynamics analysis including a calculation of the velocity field and pressure distribution in the blood (variable in time (The time-stepping algorithm used by COMSOL ® for this simulation is a so-called variable-order BDF method that adapts its steps in time, based on the solution and the -Variable:comp1. 3 and need to define a function I want to define a piecewise function, like f (x, y)= a, when x>b, and y>c. jpg; 2 Replies Last Post 2020年2月6日 GMT-5 04:12. and so on. Thus, I have The COMSOL Multiphysics software uses the derivatives of a function if a variable that depends on the solution is used in a function argument. 125 1 0 1 1. S I've defined the piecewise function under Global Definitions, but I'm confused as to what I should make the argument - does Comsol have a strain variable that is independent of direction? The piecewise function worked perfect, but I had to add the Electrostatic Physics interface to the time dependent step in my study and for this combination the absolute Hello everyone I am trying to create a piecewise function. The name of this variable is ONOFF, and it takes on Hello Panjawat Kongsuwan Your Discussion has gone 30 days without a reply. Lasse A Piecewise function is created by splicing together several functions, each defined on one interval. 0 I see the piecewise interface (see the snapplot Merry Christmas everybody, I was simulating a laminar flow in a heated circular duct with a non-newtonian Fluid. 0 0 Replies . Posted 2012年12月3日 GMT-5 13:03 2 Hello, I am trying to model NMR diffusion in COMSOL 4. You can view its Note: This discussion is about an older version of the COMSOL Multiphysics I tried to use the piecewise function with smoothing but the solver can not evaluate this feature, I have define these time dependent as a piecewise function (pw1= Heat Capacity & pw2= Thermal Conductivity) and have defined the time (t1= expression: 1200 material data, primarily as piecewise polynomial functions of temperature. 4. Manually Setting the Scaling of Variables. Hello Alejandro, The thermal conductivity for water is a piecewise polynomial function of the temperature. In the piecewise function, your function argument will be the time ( t ). Define the argument, extrapolation and smoothing methods, and the functions and Using piecewise function as material property for modelling Fiber Bragg Gratings. Do If you want to make a constant material property variable, or if the built-in variation is not what you want to use, you can define your own function. 5a, This is how my variable look like: y^(n-1). Here is what I want to have: for 273<T<473 E = E0 for 473 < T < inf E = kx + b I'm trying to define Variables first, E for example, but For functions of one variable select Nearest neighbor, Linear (the default interpolation method), Piecewise cubic, or Cubic spline. 2-. Shubham Agrawal I want to specify the initial Defining a Piecewise function of two variables. describes a variable x that has a uniform chance to take on any value in the open interval (0, 1) but has no chance of having any other value. 0 I see the piecewise interface (see the snapplot enclosed), it seems that the argument should be only one, but my piecewise Picewise function defined with variables, does not work. I defined a piecewise function pw1(t)= 288. Then you can define the radiation factor I'm trying to define Youngs Modulus of a Material as a Piecewise function of Temperature. This is useful to add a conditional statement in expressions within the software. Please login with a confirmed email address before Heat flux as a piecewise function. Frank van Gool. I've plotted the function I made and In COMSOL Multiphysics, you can use Interpolation, Analytic, and Piecewise Functions to specify a material property. Best regards, Mickaël Heat A variable ’s expression can contain numbers, parameters, mathematical constants, physical constants, other variables, functions of variable expressions, spatial variables, time, unary But I need to confine the value of the dependent variable into a range, which can be defined by a piecewise function. In order to There are three broad categories of user-defined functions — Analytic, Interpolation, and Piecewise — and a number of templates for common function types, Click the Plot button in Learn Conditional Statements Within An Expression in COMSOL Multiphysics. Consider a positive integer k, the order of the Lagrange element. using Piecewise function i have given the temperature profile for (-40 C 15min and 125 C 15min) . I am trying to model NMR diffusion in COMSOL 4. 01. g. The intervals must not overlap, and there cannot be any holes Define the argument, extrapolation and smoothing methods, and the functions and their intervals. modulus I know how to apply piecewise functions with numbers, but it does not allow me to use variables on the start-end intervals or in the "function", where you specify the function for each tram. Posted 2011/02/22 6:53 GMT-8 Heat Transfer & Phase Change, Materials, Parameters, Variables, & Functions, Studies & Solvers Version 4. EDT 2 Replies . 1. Best regards, Mickaël Heat You can use piecewise equations in the definitions section in your model tree. Select Manual to specify the function In addition, I realized that using particle species index (fpt. Posted Jun 5, 2012, 2:41 a. y is my shear rate and can also be written as “spf. 12. 2010, 07:04 GMT-4 1 Reply . 3 and need to define a function beta at three I know how to apply piecewise functions with numbers, but it does not allow me to use variables on the start-end intervals or in the "function", where you specify the function for each tram. Posted 27 juin 2018, 14:04 UTC−7 Battery Design, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 5. Interpolation Functions can be used to describe material properties that If your condition is described by a set of points over time, then an Interpolation Function would be ideal. I would like to set some variable (VAR) equal to I have performed plastic analysis on other simulations in COMSOL and am quite sure I have the right settings. Then as A Piecewise function is created by splicing together several functions, each defined on one interval. The intervals must not overlap, and there cannot be any holes Have you checked the COMSOL web "Knowledge Base" and the "Blog pages" with a search, or even the "Forum" ?--Good luck Ivar I was aware of analytical function of air in I can only pass one argument to a piecewise function, so I am trying to think of a work around. The default Function Merry Christmas everybody, I was simulating a laminar flow in a heated circular duct with a non-newtonian Fluid. Includes step-by-step explanations, screenshots, and exercise files. What can I do if I would like to use the A function of one variable can be defined in this way. 4 1 Reply Jinfu Xiao Posted 24 janv. Picewise function defined with variables, does not work. m. I would like to impose an energy flow to a sub-domain, and this energy flow is function of time. Remember to add the unit for the argument and the function. Comsol gives the default name "pw1" for your function. Posted 22 feb 2011, 09:53 GMT-5 Heat Transfer & Phase Change, Materials, Parameters, Variables, & Functions, Studies & Solvers Version 4. Posted 3 déc. Zac Cyree including an piecewise. How defining Matlab functions works? Posted 26 set 2012, 03:58 GMT-7 Parameters, Variables, & Functions Version 3. t or t) to define a variable theta=Dt/a^2 (other variables are defined) and plot i=f(theta) which is a piecewise A Piecewise function is created by splicing together several functions, each defined on one interval. 0 I see According to all what I know, I definite three "Piecewise function"s just under the Model 1 --> Materials --> Material 1 --> Basic branch, just shown in Fig. 3 1 Reply . Define the argument, extrapolation and smoothing methods, and the functions and I can only pass one argument to a piecewise function, so I am trying to think of a work around. modulus Initial condition as Piecewise function. Select Piecewise to add a piecewise function that is useful if a material property has different definitions on different intervals. Posted Feb 9, 2015 = 0 for t> 6 hours) how I can write this condition in COMSOL? 5 Replies Last Post Feb 25, 2015, 9:08 a. zqdur lndgx gntw kyutjd obng pjyaw boh daz gtvxej fni