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17 - FAQs

Q) What to do when an error message “Inner rotor outline cross over outer rotor outline” appears during a Gerotor Simulation?

Solution:

1. Make sure that, Exported CAD model with finer triangular facets.
2. Check both inner / outer centers. Inner Rotor Center and Outer Rotor Center.

If still issue is not resolved with points 1 and 2, give Additional Rotor Movement (default value) under Gerotor module.

 

Q) How to check mass conservation and correct if any imbalance is observed?

Solution: Typically, the sum of mass inflow and outflow is plotted for mass conservation. In case of imbalance check the following.

• Check for grid overlap at MGIs.

• Check for ill-posed boundary conditions.

• Check for convergence in each time-step and increase the number of iterations if required.

• Reduce convergence criterion by one order (e.g. 0.1 to 0.01).

 

Q) How to check if interfaces are properly created?

Solution: Once MGI is created, the common boundary is reflected under Interfaces. For improper interface, tolerance or projection of the MGI needs to be changed.

 

Q) How to refine the mesh near the boundary?

Solution: Select the desired boundary and change Cell Size on Boundaries.

 

Q) How to modify geometry or grid( e.g. translate, rotate etc.)

Solution: Refer to Transform Geometry or Grid.

 

Q) How to mesh the gaps in the order of microns (e.g. bearings, leakages)?

Solution: Use Annulus or any other template mesher depending on the shape of the gap.

 

Q) What to do if valve is not completely closed?

Solution: Check Closure Model and ensure radius should be lying in the valve closure region in case of Specified Radial Position method.

 

Q) Where to define time-step with multiple pump and valve modules?

Solution: Typically, time-step is defined in the pump module. However, one of the pumps has to be defined as reference pump for specifying the time-step.

 

Q) How to extract results on a surface ?

Solution: Results can be monitored and saved on existing boundaries, but only monitored on created sections. To extract results on a desired surface for further post-processing, it needs to be created and meshed before running the simulation. The meshed surface becomes an interface.

 

Q) How to monitor results of an user-defined variable ?

Solution: The user-defined variable can be displayed (contours etc.) or plotted using expressions.

 

Q) What to do if the desired output variable does not appear in the plot panel ?

Solution: The desired output variable should be switched on for the respective volume or boundary before running the simulation.

 

Q) Is it possible to couple fluid and solid models and exchange data between them in Simerics-MP/Simerics-MP+?

Solution: Yes, it is possible to perform coupled fluid-solid conjugate heat transfer simulations in Simerics-MP/Simerics-MP+ using one of the following methods.

1. Simerics-MP/Simerics-MP+ can solve combined solid-fluid simulations by meshing both the solid and fluid volumes together and effectively handling the coupling between them.
2. Script can be used to exchange data through boundary conditions between the fluid and solid (Example: Through Python). The boundary conditions are exchanged in the form of tables. The format of the tables is explained in Mapping variables using tables.

 

Q) Can we transfer CFD simulation data from Simerics-MP/Simerics-MP+ to structural simulations for stress calculation and deformation?

Solution: Yes, it is possible to transfer CFD simulation data from Simerics-MP/Simerics-MP+ to structural simulations. This is done by outputting the Pressure Distribution on the required boundaries. .