Question

A large relaxation factor will lead to ____________

(a) large and oscillatory iteration steps

(b) large and stable iteration steps

(c) small and oscillatory iteration steps

(d) small and stable iteration steps

The question was asked by my school principal while I was bunking the class.

My enquiry is from Incompressible Flows topic in section Incompressible Flows & Compressible Flows of Computational Fluid Dynamics

Answer 1

The correct option is (a) large and oscillatory iteration steps

Easy explanation: The under-relaxation factor should be large enough to move the iteration steps forward at a fast rate. But, if it is too large, the iteration steps will be unstable and oscillatory or even divergent at times.