The swimming of a bacterium or a biomimetic nanobot driven by a rotating helical flagellum is often interpreted using the resistive force theory developed by Gray and Hancock and by Lighthill, but this theory has not been tested for a range of physically relevant parameters. We test resistive force theory in experiments on macroscopic swimmers in a fluid that is highly viscous so the Reynolds n...

Classic models of fish schools and flying formations of birds are built on the hypothesis that the preferred locations of an individual are determined by the flow left by its upstream neighbor. Lighthill posited that arrangements may in fact emerge passively from hydroor aerodynamic interactions, drawing an analogy to the formation of crystals by intermolecular forces. Here, we carry out physic...

We perform a scaling analysis of the terms composing Ffowcs-Williams and Hawkings (FWH) equation, which rules propagation noise generated by rigid body in motion. Our extends seminal work Lighthill ( Proc. R. Soc. Lond. A, vol. 211, 1952, pp. 564–587) dimensional classical sources (monopole, dipole quadrupole) considering all FWH integral terms. Scaling properties are analysed light perfect/imp...

In this paper we present a high order weighted essentially non-oscillatory (WENO) scheme for solving a multi-class extension of the Lighthill-Whitham-Richards (LWR) model. We first review the multi-class LWR model and present some of its analytical properties. We then present the WENO schemes, which were originally designed for computational fluid dynamics problems and for solving hyperbolic co...

Direct numerical simulations of a turbulent boundary layer over a bump were performed to examine the effects of surface longitudinal curvature on wall pressure fluctuations (pw) and flow induced noise. Turbulence statistics and frequency spectra were obtained to elucidate the response of wall pressure fluctuations to the longitudinal curvature and to the corresponding pressure gradient. Wall pr...

SUMMARY This paper presents an extension of Lighthill, Whitham and Richards' dynamic traffic flow model (LWR) to a number of vehicle classes. Each class will be described by a separate fundamental diagram. When the various diagrams are similar in shape a scaling can be carried out that is related to the passenger-car equivalents. We present both an analytical framework and a numerical computati...

We investigate the origin of the experimentally observed multifractal scaling of vehicular traffic flows by studying a hydrodynamic model of traffic. We first extend and apply the formalism of generalized Hurst exponents H(q) to the case of random walkers that not only diffuse but rather also undergo nonlinear convection due to interactions with other walkers. We recover analytically, as expect...