CPCE CPCE Mesh Generation & Boundary Conditions

Question 1

What is the primary advantage of a structured (hexahedral) mesh over an unstructured (tetrahedral) mesh in CFD?

Accepted Answer

It typically yields lower numerical diffusion and higher solver efficiency

Answer

It is easier to generate for complex geometries

Answer

It supports more turbulence models

Answer

It requires fewer boundary condition definitions

Question 2

What boundary condition is applied at a symmetry plane in a CFD simulation?

Accepted Answer

Zero normal velocity and zero normal gradients of all other variables

Answer

No-slip condition on all velocity components

Answer

Constant pressure specification

Answer

Periodic inlet-outlet linking

Question 3

What is the purpose of mesh refinement in the boundary layer region of a CFD simulation?

Accepted Answer

To accurately resolve large velocity gradients and capture wall shear stress

Answer

To reduce total cell count and computational cost

Answer

To apply turbulence model boundary conditions

Answer

To prevent backflow at the outlet

Question 4

In CFD, what does 'mesh skewness' measure and why is it important?

Accepted Answer

The deviation of a cell's shape from an ideal equilateral form, affecting solution accuracy

Answer

The ratio of largest to smallest cell in the domain

Answer

The number of cells per unit volume

Answer

The alignment of cell faces with the flow direction

Question 5

What type of boundary condition is a 'velocity inlet' in CFD, and what quantities must typically be specified?

Accepted Answer

An inlet condition requiring velocity vector, turbulence intensity, and turbulence length scale

Answer

An outflow condition requiring pressure specification only

Answer

A wall condition requiring no-slip enforcement

Answer

A periodic condition linking inlet to outlet

Question 6

What is a 'conformal mesh' in CFD and why is it preferred over non-conformal interfaces?

Accepted Answer

A mesh where node points match exactly at shared boundaries, avoiding interpolation errors at interfaces

Answer

A mesh where all cells are the same size; preferred for uniform accuracy

Answer

A mesh generated exclusively for structured grids

Answer

A mesh that conforms to the turbulence model requirements