Thermal Casimir drag in fluctuating classical fields
  A uniformly moving inclusion which locally suppresses the fluctuations of a classical thermally excited field is shown to experience a drag force which depends on the dynamics of the field. It is shown that in a number of cases the linear friction coefficient is dominated by short distance fluctuations and takes a very simple form. Examples where this drag can occur are for stiff objects, such as proteins, nonspecifically bound to more flexible ones such as polymers and membranes. 
V. D\'emery and D.S. Dean
cond-mat.stat-mech cond-mat.soft