Simulation-Based Biological Fluid Dynamics in Animal Locomotion

Abstract

This article presents a wide-ranging review of the simulation-based biological fluid dynamic models that have been developed and used in animal swimming and flying. The prominent feature of biological fluid dynamics is the relatively low Reynolds number, e.g. ranging from 100 to 104 for most insects; and, in general, the highly unsteady motion and the geometric variation of the object result in large-scale vortex flow structure. We start by reviewing literature in the areas of fish swimming and insect flight to address the usefulness and the difficulties of the conventional theoretical models, the experimental physical models, and the computational mechanical models. Then we give a detailed description of the methodology of the simulation-based biological fluid dynamics, with a specific focus on three kinds of modeling methods: (1) morphological modeling methods, (2) kinematic modeling methods, and (3) computational fluid dynamic methods. An extended discussion on the verification and validation problem is also presented. Next, we present an overall review on the most representative simulation-based studies in undulatory swimming and in flapping flight over the past decade. Then two case studies, of the tadpole swimming and the hawkmoth hovering analyses, are presented to demonstrate the context for and the feasibility of using simulation-based biological fluid dynamics to understanding swimming and flying mechanisms. Finally, we conclude with comments on the effectiveness of the simulation-based methods, and also on its constraints.

Near- and far-field aerodynamics in insect hovering flight: an integrated computational study

“…Flapping-flying insects employ unsteady aerodynamic mechanisms to keep them afloat, and there have been many studies on this topic (Ellington, 1984a;Ellington, 1984b;Ellington, 1984c;Ellington, 1984d;Ellington et al, 1996;van den Berg and Ellington, 1997a;van den Berg and Ellington, 1997b;Dickinson et al, 1999;Liu, 2002;Liu, 2005;Sane, 2003;Lehmann, 2004a;Lehmann, 2004b;Wang, 2005). A general conclusion from these studies is that insects obtain enough lift force to support their weight through the sophisticated vortices generated by the flapping wings.…”

“…First, we image the object digitally; secondly, we segment the image to extract the object's shape as a wire frame and/or skeleton model; thirdly, we smooth and curve/surface-fit the wire frame to construct a morphological model; and finally, we render the surface and/or volume to reconstruct the object and then decompose the object in the computational domain to generate a grid. We further develop an efficient computer-aided method that unifies a morphological and kinematic modeling of 3D flyers (Liu, 2002;Liu, 2005) (H.L., manuscript in preparation).…”

“…Obtaining such a large amount of information might be extremely difficult experimentally; at this point, computational fluid dynamics (CFD)-based simulation may provide a relatively more effective method. In fact, during the last decade CFD has been widely applied to studies concerning insect flight Wang, 2000;Ramamurti and Sandberg, 2002;Sun and Tang, 2002a;Sun and Tang, 2002b;Wang et al, 2004;Miller and Peskin, 2004;Miller and Peskin, 2005;Liu, 2005). These simulation-based studies had varying degrees of success in dealing with the specific issues under consideration, but most of them were still either limited to twodimensional (2D) computations, or lacking in quantitative evaluation of the effect of wing-wing and wing-body interactions.…”

Numerical investigation of the hydrodynamics of carangiform swimming in the transitional and inertial flow regimes

“…More recently, 3D viscous self-propelled anguilliform swimming was simulated and optimized at several St on a mesh with about 3ϫ10 5 grid nodes (Kern and Koumoutsakos, 2006). Numerical simulations for swimming and flying in nature have recently been reviewed by Liu (Liu, 2005). These studies have produced important results and shed new light into the hydrodynamics of aquatic swimming.…”

Body dynamics and hydrodynamics of swimming fish larvae: a computational study

“…These models both found similar relationships between wake shape and body wave kinematics. CFD also provides more detailed 3-D flow fields than experimental flow visualization (Liu et al, 1996;Liu et al, 1997;Liu and Kawachi, 1999;Liu, 2005;Kern and Koumoutsakos, 2006;Borazjani and Sotiropoulos, 2008;Borazjani and Sotiropoulos, 2009;Borazjani and Sotiropoulos, 2010;Katumata et al, 2009). …”