A NOVEL METHOD OF GENERATING HYDROELECTRIC POWER USING LARGE COLLAPSABLE BALLOON Dr P Uday Prashant

The figure below shows the deformation of a thin- walled elastic tube which conveys a viscous flow (the direction of the flow is from left to right).

In its undeformed state, the tube is cylindrical and the ends of the tube are held open (think of a thin-walled rubber tube, mounted on two rigid tubes). As we increase the external pressure [from (a) to (d)], the tube buckles and deforms strongly. The reduction in the tube's cross sectional area changes its flow resistance and thereby the pressure distribution in the fluid, which in turn affects the tube's deformation. This is a classical example for a large-displacement fluid- structure interaction problem for which many applications exist in biomechanics e.g. blood flow in veins and arteries, flow of air in the bronchial airways.

The photograph below shows the experimental setup used to investigate the viscous flow through elastic tubes: Inside a pressure chamber, a thin-walled rubber tube is mounted on rigid tubes. A syringe pump at the upstream end pumps highly viscous silicon oil through the tubes. The volume flux and the pressure inside the pressure chamber can be controlled independently to induce the tube's collapse.

The transmural pressure at the tube's upstream and downstream end (upper and lower family of curves, respectively) is plotted against the pressure drop through the tube. The volume flux is held constant along the curves (the curves further on the left correspond to a lower volume flux). The markers (+ and x) represent the experimental data points, the straight dotted lines were obtained by a least square fit to the experimental data and the solid lines are the computational predictions.computational predictions.

The figure above shows an example of the two Finite Element meshes used to solve the problem of Stokes flow in an elastic tube.

Airway Closure: The Model Problem

Opposite wall contact and higher buckling modes

STEADY FLOW: CHOKING, FLOW LIMITATION AND ELASTIC JUMPS

Water hammer with fluid-structure interaction in thick-walled pipes A.S. Tijsseling

Hydraulic Ram Animation

A hydraulic ram or impulse pump is a device which uses the energy of falling water to lift a lesser amount of water to a higher elevation than the source. See Figure 1. There are only two moving parts, thus there is little to wear out.

FSI In liquid-filled pipes, the hydrostatic pressure at any axial location is counterbalanced by a hoop stress in the pipe wall satisfying the equilibrium condition: This hoop stress induces hoop strain and it also induces axial stress and/or strain as a consequence of Poisson contraction. This is a simple form of so-called Poisson coupling (so named because the amplitude of the interaction is proportional to the Poisson contraction ratio µ).

Skin friction acts on the whole of the interface between the liquid and the solid as a distributed axial force. The effect is known as friction coupling. At pipe junctions such as bends and branches directional changes of momentum and pressure changes due to local losses cause local axial forces in the pipe wall proportional toV.V.ρ. These are further examples of junction coupling. In a steady flow, however, they do not cause any movement of the pipe (although they sustain static deflection of the pipe).