Using high-resolution, two-dimensional hydrodynamic simulations, we investigate nonlinear gravitational responses of gas to, and the resulting drag force on, a very massive perturber Mp moving at velocity Vp through a uniform gaseous medium of adiabatic sound speed a∞. We model the perturber as a Plummer potential with softening radius rs, and run various models with differing A = GMp/(a 2 ∞rs)...

We present a novel means of transporting molecules in solution by applying a zero-time-average alternating motive force to the molecules, and perturbing the molecular drag coefficient synchronously with the applied force, thus causing a net drift in a direction determined by the phase of the alternating drag perturbation relative to the alternating force. We apply an electrophoretic form of the...

Studies of the muscle force-velocity relationship and its derived n-shaped power-velocity curve offer important insights into muscular limits of performance. Given the power is maximal at 1/3 V(max), geometric scaling of muscle force coupled with fluid drag force implies that this optimal muscle-shortening velocity for power cannot be maintained across the natural body-size range. Instead, musc...

CD = dimensionless mean drag coefficient, 2F D= fU meanD F D = drag force per unit spanwise length on the cylinder and plate, Nm 1 D = diameter of the cylinder, m E = dimensionless Young’s modulus, E = fU mean f = dimensionless oscillation frequency of the plate, f D=Umean Re = Reynolds number, fUmeanD= Umean = mean velocity at the left boundary of the channel, ms 1 V = dimensionless dilatation...

Above a critical velocity, the dominant mechanism of energy transfer between a moving object and a dilute Bose-Einstein condensate is vortex formation. In this paper, we discuss the critical velocity for vortex formation and the link between vortex shedding and drag in both homogeneous and inhomogeneous condensates. We find that at supersonic velocities sound radiation also contributes signific...

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 ...

The presence of membrane tubules in living cells is essential to many biological processes. In cells, one mechanism to form nanosized lipid tubules is via molecular motor induced bilayer extraction. In this paper, we describe a simple experimental model to investigate the forces required for lipid tube formation using kinesin motors anchored to 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) ve...

Foraging blue crabs must respond to fluid forces imposed on their body while acquiring useful chemical signals from turbulent odor plumes. This study examines how blue crabs manage these simultaneous demands. The drag force, and hence the cost of locomotion, experienced by blue crabs is shown to be a function of the body orientation angle relative to the flow. Rather than adopting a fixed orien...

Much of the current research in turbulent drag reduction centers on controlling locally individual streamwise vortices. These techniques involve complex closed loop control systems that become difficult or impossible to implement in practice. Extensive numerical simulation has suggested that introducing streamwise vorticity in the form of a transverse unsteady excitation can reduce drag far mor...

Turbulent flow is a difficult issue in fluid dynamics, the rules of which have not been totally revealed up to now. Fluid in turbulent state will result in a greater frictional force, which must consume great energy. Therefore, it is not only an important influence in saving energy and improving energy utilization rate but also an extensive application prospect in many fields, such as ship doma...