Negative Cell Volume Error While using Modify Mesh in Adjoint Solver

Why is the negative cell volume error message displayed after morphing while using the Modify Mesh tool in the Fluent adjoint solver?

1) Sometimes while using the Design Tool in the adjoint solver, an error might be reported for negative cell volume while modifying the mesh after calculating the design change.

2) This means that while morphing, a bad-quality mesh was created, leading to negative cell volumes.

3) In such cases, the prior mesh can be achieved using the Revert Mesh option as shown in the image attached herewith.

4) However, it is recommended to use the Preview Mesh option prior to morphing to get an idea about the mesh subsequent to the morphing operation.

5) The negative cell volume can be due to bad-quality mesh in base model itself, a poorly converged adjoint solution, or very high-objective functions.