We present an automatic animation system for jellyfish that is based on a physical simulation. We model the thrust of an adult jellyfish, and the organism’s morphology in its most active mode of locomotion. We reduce our model by considering only species that are axially symmetric so that we can approximate the full 3D geometry of a jellyfish with a 2D simulation. We simulate the organism’s ela...

A sharp interface immersed boundary method for simulating incompressible viscous flow past three-dimensional immersed bodies is described. The method employs a multi-dimensional ghost-cell methodology to satisfy the boundary conditions on the immersed boundary and the method is designed to handle highly complex three-dimensional, stationary, moving and/or deforming bodies. The complex immersed ...

In this paper, we investigate the stability of a fluid-structure interaction problem in which a flexible elastic membrane immersed in a fluid is excited via periodic variations in the elastic stiffness parameter. This model can be viewed as a prototype for active biological tissues such as the basilar membrane in the inner ear, or heart muscle fibers immersed in blood. Problems such as this, in...

This study is aimed at clarifying the relative importance of the specific character of the nuclei and of the duration of supercooling in heterogeneous freezing nucleation by immersed impurities. Laboratory experiments were carried out in which sets of water drops underwent multiple cycles of freezing and melting. The drops contained suspended particles of mixtures of materials; the resulting fr...

The immersed boundary method is an algorithm for simulating the interaction of immersed elastic bodies or boundaries with a viscous incompressible fluid. The immersed elastic material is represented in the fluid equations by a system or field of applied forces. The particular case of Stokes flow with applied forces on a periodic domain involves two related mathematical complications. One of the...

Microtubule gliding assays, in which molecular motors anchored to a plate drive the gliding motion of filaments in a quasi-two-dimensional fluid layer, have been shown to organize into a variety of large-scale patterns. We derive a fully three-dimensional multiscale coarse-grained model of a gliding assay including the evolution of densities of rigid filaments, bound motors, and free motors, co...

Many industrial and technological applications require precise determination of the viscosity and density of liquids. Such measurements can be time consuming and often require sampling substantial amounts of the liquid. These problems can partly be overcome with the use of microcantilevers but most existing methods depend on the specific geometry and properties of the cantilever, which renders ...

About fifty years ago Ringer demonstrated experimentally in a striking way that sodium, calcium and potassium were essential for the contraction of the heart muscle. He found that when the concentration of potassium was increased in the solution in which the heart was immersed the contractions decreased, and if the concentration was further increased the contractions became weaker and weaker, t...

We develop computational methods for the simulation of osmotic swelling phenomenarelevant to microscopic vesicles containing transformable solute molecules. We introduce StochasticImmersed Boundary Methods (SIBM) that can capture osmotically driven fluid transport throughsemi-permeable elastic membranes subject to thermal fluctuations. We also develop numerical meth-ods to handl...

Can there be infinitely many minimal hypersurfaces with a given boundary in a Riemannian manifold? A number of previous results, positive and negative, already indicated that the answer depends on the definition of surface, on orientability, on stability and minimizing properties of the surface, on the smoothness and geometry of the boundary, and on the ambient manifold. 1. Finiteness for area-...