# scallop theorem

## Contents

## English[edit]

### Etymology[edit]

From an explanation of a principle of fluid dynamics given by E. M. Purcell

### Noun[edit]

**scallop theorem** (*plural* **scallop theorems**)

- (fluid dynamics) A theorem which states that to achieve propulsion at low Reynolds number in simple (i.e. Newtonian) fluids, a swimmer must deform in a way that is not invariant under time-reversal.