Fig. 4
From: Oscillatory interactions of two spheres in an unbounded couple stress fluid

Drag force versus time t for different values of first couple stress parameter with \(a_2/a_1=2.0, \bar{\eta }'=0.01,U_2/U_1=0.5,\delta =4.0\) for low frequency at \(\alpha =0.5\) (a) in-phase, (b) out-of-phase.