Question

Which statement is not true regarding the variables present in the viscous flow problems?

(a) Velocity components are zero on fixed walls

(b) Shear stress is zero along the line of symmetry

(c) Vertical velocity component vy and horizontal stress tx must be zero along the horizontal line of symmetry

(d) Shear stress is non zero along the line of symmetry

I got this question during an interview.

This key question is from Governing Equations topic in section Flows of Viscous Incompressible Fluids of Finite Element Method

Answer 1

The correct choice is (d) Shear stress is non zero along the line of symmetry

Easiest explanation: In general, the primary variables are obtained using FEM and secondary variables are calculated using the primary variables. In the viscous flow, both the velocity components are zero on fixed walls, and shear stress is zero along the line of symmetry. Vertical velocity component vy and horizontal stress tx must be zero along the horizontal line of symmetry and vx, ty must be zero along the vertical line of symmetry.