comsol use previous solution as initial condition

These … Posted 9. nov. 2017 14.38 GMT-8 Microfluidics, Modeling Tools, Studies & Solvers Version 5.3 1 Reply COMSOL MULTIPHYSICS | 5 the initial values, which makes it possible to plot and evaluate the solution and any solution-dependent variables using the initial values as the solution. How can I use a previous solution as inital condition? Using stationary computational results as the initial condition for time-dependant solution. Previous Solution Operator in Transient Modeling read 0 Replies 1329 Views. The diffusion analysis required use of a stepped boundary condition on the surface of the part. To do this I am using a very simple model (see description down below) but I seem to be unable to get it to work. ?Subscribe - https://bit.ly/3q7M2xk This operator allows you to evaluate quantities at the previous time step when using the default implicit time-stepping algorithm. The State Variable feature simplifies the tracking of the history of a field over time. Posted Oct 23, 2012, 5:57 PM EDT RF & Microwave Engineering, Modeling Tools, Parameters, Variables, & Functions, Studies & Solvers Version 4.3a 1 Reply 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. Send Private Message Flag post as spam. Today, we will introduce a goal-seeking equation into a model in the COMSOL Multiphysics® software that is used in combination with a fully coupled approach to solving a nonlinear problem. solution as initial values for the next study. Using stationary computational results as the initial condition for time-dependant solution. It was linearized by taking the solution from the previous timestep to calculate the parameters that depend on the primary variable. Using previous solution as initial values. There, you can select method as solution and solution as the previous solver, and also if its time dependent you can select the specific time as the initial condition. Posted 08.02.2012, 10:40 GMT-8 Heat Transfer & Phase Change, Studies & Solvers Version 4.2 5 Replies This is for COMSOL 5.2, but should be similar for 4.2: Create the stationary study. Using Global Equations to Introduce Fully Coupled Goal Seeking. Using the Previous Solution Operator in Transient Modeling. COMSOL Multiphysics version 5.1 includes a Previous Solution operator within time-dependent studies. This operator allows you to evaluate quantities at the previous time step when using the default implicit time-stepping algorithm. Yes, You can do so if you use 2 different solvers. Posted 3 mars 2021 à 00:51 UTC−8 General, Modeling Tools, Equation-Based Modeling Version 5.5 1 Reply The COMSOL discussion forum covers a wide variety of simulation topics. Today, we will demonstrate the steps we outlined with a 3D generator model example, comparing our results with an analogous 2D model. Shriram. The Previous Solution operator is used since we simply want to change the surface emissivity once the temperature gets above the specified value and leave it otherwise unchanged. We have already introduced the use of the Previous Solution operator in a previous blog entry. Using 2D solution as initial condition for 3d simulation Posted Jun 22, 2012, 6:42 AM EDT Studies & Solvers Version 4.3 7 Replies fcurtis The workaround is to start from some arbitrary initial distribution, ( , )≠0, and to make iterations successively converging to the desired nontrivial solution of (1). COMSOL Multiphysics provides the solution at that time using interpolation. Comsol: How to use initial conditions of previous study for next study.Continuous Solution! this has been discussed a couple of times earlier I believe, at lieast similar demands, try an "advanced search" on "boundary conditions" "GO", just below the "DISCUSSION FORUM" banner. January 20, 2021. The sweep continues in such a way until “visc_ramp” reaches a value of 1, which … In the second solver, under dependent variables, look at initial values (2nd heading). The choice of a monotonic (0,) ... the moving cluster surface using COMSOL’s Moving Mesh interface. We have already introduced the use of the Previous Solution operator in a previous blog entry. The 'initial values' condition only allows to put initial constant displacement. The "Values for dependent values" in study step settings should be set to the default ("Physics-controlled" in 5.2). When you are solving a transient model, the COMSOL software by default uses an implicit time-stepping algorithm with adaptive time step size. COMSOL Multiphysics version 5.1 includes a Previous Solution operator within time-dependent studies. 2012 à 02:21 UTC−8 Studies & Solvers, Structural Mechanics & Thermal Stresses Version 4.2 4 Replies Yes, You can do so if you use 2 different solvers. Buckling, When Structures Suddenly Collapse. Answer to Use comsol to perform the calculation results. Posted 13 dec. 2016 05:44 GMT−8 Version 5.2a 3 Replies . However, one has to be careful, as an over-specification of an initial guess can harm the iterative solver process. COMSOL always returns the trivial solution, u(x,y)=0. How to Use Solutions from Previous Study as Initial Conditions. March 7, 2014. Posted 12 juin 2019 à 12:44 UTC−4 Mechanical, LiveLink for MATLAB, Parameters, Variables, & Functions Version 5.4 0 Replies by Henrik Sönnerlind. The concepts of sector symmetry and periodic boundary conditions, including … Using 2D solution as initial condition for 3d simulation Posted 22-Jun-2012, 6:42 am GMT-4 Studies & Solvers Version 4.3 7 Replies fcurtis You can use the at operator to compare two solutions at different times during results evaluation; for example, at(30,u)-at(20,u) is the difference between the solution at 30 s and the solution at 20 s. This will use the initial conditions you specified in your physics setting (usually 0 is used in the physics settings). The space coordinate \mathbf{x} represents all three directions (x, y, and z) in this case.. Let us take a look at how this operator is implemented and then examine how it can be used for various modeling needs. In a previous blog entry, we showed you how to model rotating machines, like motors and generators, using the Rotating Machinery, Magnetic interface in COMSOL Multiphysics. The non-linear balance equation was implemented using the coefficient form of the PDE interface. Shriram. ?Subscribe - https://bit.ly/3q7M2xk by Walter Frei. The latter takes place because the trivial solution is one of the solutions to equation (1). Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here. I am trying to get familiar with how to use results from a previous solution as initial conditions in a new solution. Using results or a previous simulation as initial condition and change loads. I am trying to get familiar with how to use results from a previous solution as initial conditions in a new solution. Using results or a previous simulation as initial condition and change loads. Here, P denotes a differential operator, u the dependent variable (the solution variable), F a source, f a function that describes the initial condition, B an operator, and g a function at the boundary. ... boundary condition for coefficient form PDE read 0 Replies 436 Views. There, you can select method as solution and solution as the previous solver, and also if its time dependent you can select the specific time as the initial condition. Is that feasible? The COMSOL discussion forum covers a wide variety of simulation topics. In this blog post, we will investigate some classes of buckling problems and how they can be analyzed. Posted Oct 23, 2012, 5:57 PM EDT RF & Microwave Engineering, Modeling Tools, Parameters, Variables, & Functions, Studies & Solvers Version 4.3a 1 Reply 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. In the second solver, under dependent variables, look at initial values (2nd heading). Today, we will introduce a goal-seeking equation into a model in the COMSOL Multiphysics® software that is used in combination with a fully coupled approach to solving a nonlinear problem. Using Global Equations to Introduce Fully Coupled Goal Seeking. Two classes of time-stepping algorithms are available: a backward difference formula (BDF) and a generalized-alpha method. Thanks for … For that I would like to do a simulation with the first two material, then use this solution as input for the three-material case, solve it, and so on. Initial conditions (steady state) to time dependent model Posted 14-Aug-2014, 1:29 pm GMT-7 Studies & Solvers Version 4.4 5 Replies Aaron Shifman Browse the threads and share your ideas with the COMSOL community. Posted 13 févr. If you are doing a frequency sweep, I think by default Comsol will use a solution from the previous frequency as an initial guess for the current one. Using previous solutions as initial conditions for next step in a study. Comsol: How to use initial conditions of previous study for next study.Continuous Solution! January 20, 2021. In this study I set the "Initial values of variables solved for" to User controlled - Solution - Study 1 - Last. However, the stress at time zero is still much lower that the last time step in Study 1. I would be very greatful for any help on what I might do wrong or if I can do this another way. Set solution of previous time step as initial condition. This has the advantage of being unconditionally stable for many classes of problems and it lets the software choose the optimal time step size for the specified solver tolerances, thereby reducing the computational cost of the solution. using previous COMSOL solution as initial value for another solution. Florian Tomiak . this initial condition is beyond the scope of this paper; however, (0,) ... therefore model growth with this solution as initial concentration. In many cases we need to break a simulation into smaller parts. 2012 à 02:21 UTC−8 Studies & Solvers, Structural Mechanics & Thermal Stresses Version 4.2 4 Replies If you are doing a frequency sweep, I think by default Comsol will use a solution from the previous frequency as an initial guess for the current one. However, a physically unrealistic result (local concentrations above initial value with drying of the epoxy material) was found in the solution … And ... in the square plate 05.xs 24, Os y s 24 whose upper side is kept at potential 25°C sides are kept at The solution is given by u(x, y) = § 4, sin 1) 0°C. Posted 13 févr. The auxiliary sweep will find a solution for the first value of “visc_ramp” (1000) and use this solution as the initial condition for solving the next value of “visc_ramp” (100). Posted 08.02.2012, 10:40 GMT-8 Heat Transfer & Phase Change, Studies & Solvers Version 4.2 5 Replies Browse the threads and share your ideas with the COMSOL community. The COMSOL discussion forum covers a wide variety of simulation topics. However, one has to be careful, as an over-specification of an initial guess can harm the iterative solver process. The mathematical model may describe a physical phenomenon such as fluid flow. Buckling instability is a treacherous phenomenon in structural engineering, where a small increase in the load can lead to a sudden catastrophic failure. to "simply" turn on and off a value you can set a conditional "*(t<0.5)" on your value (if you are in time domain, or *(Param<3) if you are running a parametric sweep with "Param" as parameter. How to Use Solutions from Previous Study as Initial Conditions. The Previous Solution operator is used since we simply want to change the surface emissivity once the temperature gets above the specified value and leave it otherwise unchanged. uptake have therefore been transferred to COMSOL Multiphysics® in form of an equation-based model. † Compute commands are now available for individual study steps (without opening the solver sequence): When applicable, each study step includes options to Compute Let us take a look at how this operator is implemented and then examine how it can be used for various modeling needs. When you are solving a transient model, the COMSOL software by default uses an implicit time-stepping algorithm with adaptive time step size. To combine the Relaxation Method with the Adaptive Mesh Refinementit is advisable to apply multiple studies, each next study using the solution of the previous one as the initial condition, each applying the Adaptive Mesh Refinement. by Walter Frei. To resolve the kink structure one can use the Adaptive Mesh Refinement feature of COMSOL.

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