**In some cases mesh deformation can result in negative volumes and hence solver failure. How to avoid this?**

- Use a different Mesh Stiffness option. The default option may not be appropriate for your particular model.

- Modify the Model Exponent. If negative volumes are occurring on the boundaries, increase the exponent. If negative volumes are occurring away from the boundaries, try reducing it from the default value.

- Use the double precision solver

- Set the convergence criteria for the Mesh Displacement equation to a lower value (e.g. 1E-05) and increase the coefficient loops to 10 or higher in CFX-Pre under Solver Control->Equation Class Settings->Mesh Displacement