Comsol convergence criteria You can use Aug 17, 2022 · The external field is applied to the boundaries of the system. This must be a numerical value evaluated over some, or all, of the nodes in your mesh. I am currently working on a topic related to the simulation of fluid flow within a test loop section (inlet d = 3mm + rack + 4 titanium steam generator tubes with a diameter of 17mm) and I am encountering a problem with the simulation. EDT Fluid & Heat, Computational Fluid Dynamics (CFD), Geometry, Mesh, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4. Jan 13, 2022 · Convergence criteria of the segregated solver are met but not all conditions for group velocity u, pressure p are fulfilled. PST Version 5. EDT Version 4. In space, the default is 2nd-order Lagrange elements. EDT by Julien Givernaud Sep 19, 2013 · Convergence criteria Posted 2013年9月19日 GMT-4 15:14 Studies & Solvers Version 4. 36 * 1E-03) Steady-state study (solver Jul 8, 2013 · Comsol does not finish the calculation even though convergence criteria is satisfied Posted Jul 8, 2013, 5:44 a. You may want to look into the company convergence criteria. Time Dependent in the COMSOL Multiphysics Reference . Examine the nonlinearities in your model and any feedback conditions and try to estimate what kind of response they will produce for your given inputs. PDT Fluid & Heat, Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD), Studies & Solvers Version 4. Linear in the COMSOL Multiphysics Programming Reference Manual. May 10, 2015 · How to set convergence criteria? Posted May 10, 2015, 10:46 a. It most often occurs when using a direct solver for the linear solver. 5 1 Reply Jan 18, 2024 · How to reduce the convergence error for nonlinear solver? Posted Jan 18, 2024, 1:46 a. Generalized- α introduces some numerical damping of high frequencies but much less than the BDF method. 0, Version 5. The convergence of any physical problem is directly related to the Relative Tolerance. Any trademarks referenced in this document are the property of their respective owners. 4, Version 5. About the Convergence Plot and Progress Window The gradient-based solvers create a Convergence Plot that displays the number used for the Convergence criteria as a function of the iteration numbers; see About Optimality Tolerances. Mar 22, 2013 · Hi I have understood it's iterating, over the different steps, but in the specified order, until the convergence criteria is reached, but I do not have any definitive answer, the only way to find out is to once follow carefully what COMSOL does in the solver sequences, you have the log (also a detailed view but it does not bring much more), and you can follow in the solver sequence view during For information about the convergence criteria used by the iterative solvers, see Convergence Criteria for Linear Solvers Comsol does not finish the calculation even though convergence criteria is satisfied 5 Replies 4357 Views Version 4. EST 1 Reply The following section provides more detailed information about the Iterative solver types: GMRES, FGMRES, Conjugate Gradients, BiCGStab, and TFQMR. 2 30 Replies The COMSOL Multiphysics software uses a Newton-type iterative method to solve nonlinear systems of PDEs. EDT reply 1 decade ago on Jul 22, 2013, 8:59 a. Posted 2020年4月21日 GMT-4 13:19 Electromagnetics, Fluid & Heat, Battery Design Version 5. Pseudo time stepping is available for stationary problems. EDT Studies & Solvers Version 4. 3b 0 Replies Apr 21, 2020 · Convergence criteria of the segregated solver are met but not all conditions for group Heat transfer are fulfilled. In the coupled approach, it functions together with the constant damped Newton solver. Sep 19, 2013 · Convergence criteria Posted Sep 19, 2013, 3:14 p. With a Time-Dependent Solver, also select the Limit on nonlinear convergence rate check box to force the nonlinear solver to terminate as soon as the convergence is estimated to be too slow. Apr 29, 2019 · Convergence criteria of the nonlinear solver are met but not all linear solver conditions are fulfilled. The property maxsegiter is only supported when tol is used for termination. See the settings for and for related parameters. This solution method can be sensitive to the initial estimate of the solution. EDT Computational Fluid Dynamics (CFD) Version 4. 3b 0 Replies Oct 13, 2015 · Setting up convergence criteria in Multiphysics Problem Posted Oct 13, 2015, 6:33 a. Solving this model often results in the above mentioned error: Convergence criteria of the nonlinear solver are met but not all linear solver conditions are fulfilled, when the nonlinear magnet starts to saturate. Here you refine the mesh and run the study again, and then check if the solution is converging to a stable value as the mesh is refined. 3b 5 Replies May 21, 2018 · Convergence criteria of the nonlinear solver are met but not all linear solver conditions are fulfilled. The Anderson acceleration method is primarily intended for acceleration of nonlinear iterations in transport problems involving, for example, crosswind diffusion stabilization. Aug 6, 2013 · Implementing a Mesh Refinement Study In order to implement a mesh refinement study in COMSOL Multiphysics, you must first decide what output parameter you will use for your convergence criteria. If the solution shoots off to infinity due to positive feedback, for example, the solver will not be able to capture this. Oct 20, 2023 · UPDATE: I found this message in the Log: "Convergence criteria of the segregated solver are met but not all conditions for group Heat transfer are fulfilled. Apr 21, 2020 · Convergence criteria of the segregated solver are met but not all conditions for group Heat transfer are fulfilled. ", so I am assuming there is something where with the conditions I set up for the Heat Transfer. 3b Computational Fluid Dynamics (CFD) Christian Walter posted 1 decade ago Jul 8, 2013, 5:44 a. I have included snapshots of the 'progress' and the 'log', also showing the convergence for the segregated solver and GMRES. Want to learn about improving convergence when solving a nonlinear stationary model in COMSOL Multiphysics®? If so, check out this article. 3b 0 Replies Dec 23, 2013 · This post examines techniques for accelerating the convergence of multiphysics problems using the Fully Coupled and Segregated algorithms. Sep 19, 2013 · Convergence criteria Posted 2013/09/19 15:14 GMT-4 Studies & Solvers Version 4. EDT 0 Replies If a model has not been verified by other means, a convergence test is useful for determining if the mesh density is sufficient. The chosen physics: Laminar flow (Re = 9 / Velocity = 2. You can track a variable or mathematical expression of variables at a single point of interest, or you can use By default, COMSOL Multiphysics uses the implicit second-order accurate method generalized- α to solve transient acoustics problems. Browse the threads and share your ideas with the COMSOL community. I have coupled electric, transport of species, momentum and heat transfer in my model. One effect of changing scaling of one variable in a multi variable problem is the relative accuracy. 3a 0 Replies Mar 14, 2013 · Convergence behaviour in a stationary solver Posted Mar 14, 2013, 1:06 p. I am ramping up my drain voltage value but at some higher values of voltage, when I run the model each time I get an error while simulating as "Convergence criteria of the nonlinear solver are If/when you come across a physics/coupling that is blowing up your convergence, try a simplifying test case where you take only the problematic one and verify that the boundary conditions and chosen solver work in isolation. Posted Jan 9, 2014, 5:42 a. EST Fluid & Heat, Computational Fluid Dynamics (CFD), Studies & Solvers Version 4. Consult For information about the convergence criteria used by the iterative solvers, see Convergence Criteria for Linear Solvers Sep 25, 2019 · The program is able to perform the computation with complete convergence, showing 100% for 'solution 1', however it fails to end the computation and continues iterating on GMRES untill I cancel the computation. If the solution changes when you refine the mesh, the solution is mesh dependent, so the model requires a finer mesh. 3b 0 Replies For information about the convergence criteria used by the iterative solvers, see Convergence Criteria for Iterative Solvers The COMSOL discussion forum covers a wide variety of simulation topics. EDT Studies & Solvers Version 5. It also discusses the Convergence Criteria for Linear Solvers and Selecting a Preconditioner for an Iterative Linear System Solver. For example, for a nonlinear time-dependent model, the menu that contains the nonlinear solver and Time-Dependent Solver (Generalized-alpha) as options. If the initial conditions are too far from the desired solution, convergence might be impossible, even though it might be simple from a different starting value. 3a 5 Replies Want to learn about different techniques for improving convergence when computing semiconductor models? Check out this article. For information about the convergence criteria used by the iterative solvers, see Convergence Criteria for Linear Solvers Anderson acceleration, which is a nonlinear convergence acceleration method that uses information from previous Newton iterations to accelerate convergence. Convergence criteria of the segregated solver are met but not all conditions for group mass fraction are fulfilled. 6 0 Replies The third available option for segterm is itertol, which is a combination of the other two options; the segregated iterations are terminated when one of the two convergence criteria of tol and iter is met. 2a, Version 4. The scaling factors play a role. 3 0 Replies To control which solvers generate convergence plots, click the Convergence Plot Settings () button in The Progress Window toolbar to select or clear the convergence plots for each solver. Convergence is allowed when this number is one and the usual convergence criteria are met. m. 3a, Version 4. To control which solvers generate convergence plots, click the Convergence Plot Settings () button on The Progress Window toolbar to select or clear the convergence plots for each solver. 3b 0 Replies Mar 10, 2013 · What is convergence? Posted Mar 10, 2013, 11:37 a. Posted May 21, 2018, 11:53 a. For the Residual termination criterion, the segregated solver terminates when the following convergence criterion is satisfied: For all the groups j, the error estimate is smaller than the corresponding tolerance, , where where F is the current residual, and are the weights determined by the first and, if applicable, the second residual. 3b, Version 4. For the time dependent model, the tolerance could be changed by the steps outline above. Jan 9, 2014 · Absolute tolerance convergence criteria for flow simulations. COMSOL makes every reasonable effort to verify the information you view on this page. Resources and documents are provided for your information only, and COMSOL makes no explicit or implied claims to their validity. COMSOL does not assume any legal liability for the accuracy of the data disclosed. Posted Apr 29, 2019, 4:44 p. 3, Version 4. Posted Jan 13, 2022, 7:35 p. Apr 15, 2025 · Hello, I have a Comsol license within the company Framatome. The convergence criterion in Equation 20-9 states that the iterations terminate when the relative (preconditioned) residual times the factor ρ is less than a tolerance tol. 0a1 lmmx w7ufis rpdunednr opx i9ean nfg3vy hgh plsb bhmvrl