Instabilities in rotating channel flow

What is it about?

Two kind of instabilities can prevail in channel flow - either exponential or transient (algebraic). When rotation is introduced, strong exponential instabilities can be excited readily. We look at the algebraic instability, and examine if they too can play a role in the dynamics despite exponential instabilities.

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Why is it important?

This is a case where two different types of instability can act in cohesion to drive the system towards a turbulent state. When exponential instabilities are typically found, transition is inevitable and hence other linear processes may be disregarded. We show that algebraic instabilities can still cause transition even when exponential instabilities exist, and in fact accelerate the process. This kind of a study is always relevant for shear flows where exponential instability has already been established.