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CFD-based Evaluation of Drag Force on a Sphere Unsteadily Moving Perpendicularly toward a Solid Surface: a Simple Model of a Biological Spring, Vorticella Convallaria

S. Ryu[1], and P. Matsudaira[2]
[1]Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
[2]Department of Biology and Bioengineering, Massachusetts Institute of Technology, Cambridge, MA, USA
Published in 2008

Vorticella convallaria, a sessile peritrich ciliate having a contractile stalk, is regarded as a model biological spring because of its remarkably fast contraction. Because the cell body shrinks to sphere-like shape during contractions, it can be assumed to be a sphere moving in quiescent water, and Vorticella’s contraction force has been evaluated with Stokes’ law.

In this study, we evaluate the contraction force of Vorticella with COMSOL CFD simulations assuming the body to be a sphere unsteadily moving perpendicularly toward a wall and show that effects of accelerated motion of the body and the substrate must be considered in evaluating the contraction force of Vorticella.

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