The Solution to the Most Common Errors on SimScale

BlogTips & TricksThe Solution to the Most Common Errors on SimScale

errors SimScale simulation software

Every now and then, users experience some errors while using SimScale for their simulations. The engineering team is constantly working on preventing most of them, but as with any software—especially a CAE one—errors that depend on the way it is used cannot be prevented by the provider. Having errors can be frustrating, but the good news is that you can learn how to solve them, which can turn to be a real treasure.

In this article, the most commonly occurring errors on SimScale will be covered, taking into consideration all available analysis types and solvers. Let’s get started first with CFD:

Common CFD Errors on SimScale (OpenFOAM)

Maximum number of iterations exceeded

Maximum number of iterations exceeded by the solver

This error appears when the solver has iterated 1000 times in a particular time step but could not reach the tolerance specified by the user. This can occur due to a bad mesh having illegal/bad cells or a flow variable reached a very high or non-physical value.

For a detailed solution to overcome this error, please visit this page.

Floating point exception

The simulation has encountered a floating point exception

The simulation sometimes might fail, giving a floating point exception, possibly due to a division by zero that it has encountered while solving. Specifically, this can occur while performing a Compressible and Natural Convection Heat Transfer analysis, forgetting to either define a pressure boundary condition and reference pressure value or a zero value is defined will lead to this error.

For a detailed solution to overcome this error, please visit this page.

System out of memory

The system ran out of memory

This error occurs if the memory requirement of the solver exceeds the available machine memory. It can be due to a large mesh being used for the simulation, which requires more memory to solve. Using the same mesh either on a bigger machine or reducing the mesh size can help here.

For a detailed solution to overcome this error, please visit this page.

Meshing Error: Material point is out of bounds

The ‘Material Point’ specified was located outside the ‘BaseMeshBox’, which is considered fatal. It must be located inside the BaseMeshBox

This error appears while meshing if the defined material point (under Geometry Primitives sub-tree) for Hex-dominant parametric is defined outside the BaseMeshBox. In this case, double check the coordinates of the material points. The best practice is to have a material point from your CAD tool and then input the same coordinates on SimScale.

For a detailed solution to overcome this error, please visit this page.

Continuity Error encountered cannot be removed

A continuity error has been encountered that cannot be removed

An error encountered by the solver while solving the continuity equation which can’t be removed, i.e., the solver will keep on trying to solve but will fail consistently. Normally it’s due to an issue in the Boundary Condition setup as the inlet and outlet flow rates are not equal.

For a detailed solution to overcome this error, please visit this page.

Common FEA errors on SimScale (CalculiX*)

Too many cutbacks

No convergence could be reached. Try to decrease the initial time step length of auto-time stepping. If the physical contact is involved, then try to adjust its parameters so that convergence can be reached easily

If the auto-time stepping is selected, then this error appears when the solver tries to solve some kind of nonlinearity and reaches the lowest limit of the increment size, after which it cannot decrease anymore. This can be solved for example by making the Initial time step length smaller.

For a detailed solution to overcome this error, please visit this page.

Overconstrained degrees of freedom (DOF)

At least one node is over-constrained for the current settings. Please check your boundary conditions for incompatible settings

The solver failed due to overconstrained degrees of freedom (DOF) of either one or more entities. This can occur due to multiple reasons. It can be due to either restricting a node/s multiple times in the same direction or multiple slave surfaces sharing same node/s in a contact definition.

For a detailed solution to overcome this error, please visit this page.

Memory allocation problem

 The solver could not allocate the memory for the calculation. Please increase the number of computing cores under Simulation Control

This error occurs because the solver has failed to allocate the memory required for the analysis. In this case, either make the mesh smaller or increase the size of the machine. You can also consider requesting lesser solution fields and recording fewer time steps.

For a detailed solution to overcome this error, please visit this page.

Common FEA errors on SimScale (Code_Aster**)

Timestep bigger than simulation interval

Timestep bigger than the given simulation interval. Please adapt your simulation control settings

This error appears when the total simulation time is larger than the initial time step. For example, setting a total simulation time of ‘1’ and an initial time step of ‘2’ will lead to this error.

For a detailed solution to overcome this error, please visit this page.

No physical contact resolution under certain fixed point iterations

A problem in physical contact resolution. The solver was unable to resolve the contact under specified fixed point iterations. Either change your master or slave assignment or decrease the value of penalty coefficient under contact

If the penalty contact solution method is used, then this error will appear if the contact can’t be resolved under the defined number of fixed point iterations. This can appear either due to wrong master and slave assignment or if a very high penalty coefficient is set.

For a detailed solution to overcome this error, please visit this page.

Shared slave nodes

The slave entities of two contact definitions share nodes. If there is not the same entity assigned as slave, this might be caused by shared edges

This error appears when two defined slave surfaces in multiple contact share nodes with each other. For example, if two bonded contacts are defined and the slave surface of one of the defined contact has the other defined contact slave surface as the neighboring surface.

For a detailed solution to overcome this error, please visit this page.

Memory allocation

Memory allocation error. In order to prevent this behavior please choose a bigger machine with less computing cores

Similar to a non-advanced solver, this error appears when, for a bigger problem, a smaller machine is selected which cannot allocate the memory required by the solver. Similarly, it is possible to either make mesh coarser or choose a bigger machine.

For a detailed solution to overcome this error, please visit this page.

Material law integration

An error occurred due to material law integration problem. Please check your material parameter units or try to use automatic time-stepping scheme rather than manual with smaller initial time steps under Simulation Control

This error appears if solver fails to solve the material nonlinearity in a given time step or even after cutting the time step until it reaches a specific threshold. This can be either due to non-consistent units or a large initial time steps definition.

For a detailed solution to overcome this error, please visit this page.

Uninvertible matrix

Solution diverged as the matrix is singular. This may be caused by an unconstrained rigid body motion, incoherent material parameters or a body is held only by a contact

The solver failed due to an ill-conditioned boundary condition, mismatched material units or a structure that is held only by a contact in the case of contact analysis. For example, an ill-conditioned boundary condition could be that a force is applied to a face of the structure but it is not constrained, therefore leading to a rigid body motion.

For a detailed solution to overcome this error, please visit this page.

Matrix not factorable

The solution matrix is not factorable. This might be caused by an unconstrained rigid body motion or by over-constrained degrees of freedom due to multiple linear relations at least one node

The solution diverged due to solution matrix being singular i.e. non-invertible. This error may appear due to several reasons including over-constrained nodes in a system, multiple contact assignments in reverse order, slave surface sharing nodes etc.

For a detailed solution to overcome this error, please visit this page.

*   Related to all non-advanced solvers

** Related to all advanced solvers


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