Question

When do we use a constant pressure boundary condition?

(a) When there is an impermeable boundary

(b) When there is constant pressure

(c) When we do not know the flow distribution but we know the pressure at the boundaries

(d) When we do not know the pressure at the boundaries

The question was posed to me by my school teacher while I was bunking the class.

My enquiry is from Boundary Conditions topic in portion Boundary Conditions of Computational Fluid Dynamics

Answer 1

Right option is (c) When we do not know the flow distribution but we know the pressure at the boundaries

To elaborate: When the flow distribution including velocity are not properly known but the boundary pressures are known, a constant pressure boundary condition is used.