Fluid-structure interaction on Shreyas Mandre

Oscillating hydrofoil for hydrokinetic power

Thu, 01 Jun 2017 00:00:00 +0000

Between 2013 and 2017 I led an ARPA-E programme at Brown University that took an oscillating hydrofoil for tidal and river power from the equations to 1 kW and 2 kW devices tested in the Taunton River and the Cape Cod Canal — technology readiness level 1 to 6. The physics is the lift a foil keeps after the flow separates from its leading edge, a cousin of the vortex-driven waving of marine grass; the engineering is a machine that turns it into power under both directions of the tide.

Waving marine grass

Mon, 04 Jan 2016 06:08:23 +0000

I bet you have seen gusts of wind exciting synchronized waves on the surface of tall grass field just like observed on the beach.

Fluid-structure instability

Sat, 22 Aug 2026 00:00:00 +0000

A university course on the instabilities that arise when a fluid flow and a deformable structure interact. (Taught at Cambridge as 4A10, Flow Instability and Fluid-Structure Interaction.) The HTML and PDF lecture notes may be found at this link. Here is the learning material:

Elastohydrodynamics of contact in adherent sheets

Mon, 22 Aug 2022 00:00:00 +0000

Adhesive contact between a thin elastic sheet and a substrate arises in a range of biological, physical and technological applications. By considering the dynamics of this process that naturally couples fluid flow, long-wavelength elastic deformations and microscopic adhesion, we analyse a sixth-order thin-film equation for the short-time dynamics of the onset of adhesion and the long-time dynamics of a steadily propagating adhesion front. Numerical solutions corroborate scaling laws and asymptotic analyses for the characteristic waiting time for adhesive contact and for the speed of the adhesion front.

A generalized theory of viscous and inviscid flutter

Wed, 07 Oct 2009 00:00:00 +0000

We present a unified theory of flutter in inviscid and viscous flows interacting with flexible structures based on the phenomenon of 1 : 1 resonance. We show this by treating four extreme cases corresponding to viscous and inviscid flows in confined and unconfined flows. To see the common mechanism clearly, we consider the limit when the frequencies of the first few elastic modes are closely clustered and small relative to the convective fluid time scale.

The feasibility of generating low-frequency volcano seismicity by flow through a deformable channel

Tue, 01 Jan 2008 00:00:00 +0000

Oscillations generated by flow of magmatic or hydrothermal fluids through tabular channels in elastic rocks are a possible source of low-frequency seismicity. We assess the conditions required to generate oscillations of approximately 1 Hz via hydrodynamic flow instabilities (roll waves), flow-destabilized standing waves set up on the elastic channel walls (wall modes), and unstable normal modes ringing in an adjacent fluid reservoir (clarinet modes). Stability criteria are based on physical and dimensional arguments, and discussion of destabilized elastic modes is supplemented with laboratory experiments of gas flow through a channel in a block of gelatine, and between a rigid plate and a rubber membrane.