This paper presents a variational multiscale method (VMS) for the incompressible Navier–Stokes equations which is defined by a large scale space LH for the velocity deformation tensor and a turbulent viscosity νT . The connection of this method to the standard formulation of a VMS is explained. The conditions on LH under which the VMS can be implemented easily and efficiently into an existing f...

This study addresses the issues pertinent to both the topographic effects on wind flow fields over complex terrain and the accuracy of computational fluid dynamics (CFD). The numerical simulations using isotropic eddy viscosity and wall functions are conducted based on the numerical solutions of the incompressible, nonisothermal, steady-state turbulent flows, in which a regional computational m...

Recently, a new approach for the stabilization of the incompressible Navier-Stokes equations for higher Reynolds numbers was introduced based on the nonlinear differential filtering of solutions on every time step of a discrete scheme. In this paper, the stabilization is shown to be equivalent to a certain eddy-viscosity model in LES. This allows a refined analysis and further understanding of ...

In this work we propose an effective viscosity criterion for the stabilization of annular gas-liquid and liquid-particle flows and an inertial mechanism which drives waves into slugs in slugging gas-liquid flows. Annular flow is stable when the fluid having the higher effective viscosity occupies the core region and the lower viscosity fluid is the annulus. The eddy viscosity criterion is shown...

In this paper we provide an error analysis of a subgrid scale eddy viscosity method using discontinuous polynomial approximations, for the numerical solution of the incompressible Navier-Stokes equations. Optimal continuous in time error estimates of the velocity are derived. The analysis is completed with some error estimates for two fully discrete schemes, that are first and second order in t...

A = constant b = vortex spacing C = constant to adjust turbulent spreading q = rms turbulence velocity R = mean radius T = parameter for vortex age t = time u = axial velocity v = lateral velocity w = descent speed y = spanwise coordinate, positive for port vortex z = vertical coordinate, positive pointing upwards = circulation = eddy dissipation rate = standard deviation = (effective) kinemati...

We describe the use of eddy current brakes as fast turn-on, tunable, linear dampers for haptic rendering using a prototype haptic device outfitted with eddy current brakes. We show that at the speeds typically required for haptic interaction, eddy-current-induced drag is proportional to velocity. We also show that a modulation rate of approximately 250 Hz can easily be achieved with off the she...

In this paper we provide an error analysis of a subgrid scale eddy viscosity method using discontinuous polynomial approximations for the numerical solution of the incompressible Navier–Stokes equations. Optimal continuous in time error estimates of the velocity are derived. The analysis is completed with some error estimates for two fully discrete schemes, which are first and second order in t...

breaking waves have ability to transport large quantities of sediment and significant impact on coastal structures morphology. hence, modeling of wave breaking is an important subject in coastal and marine engineering. in this research, the periodic wave breaking process on a plane slope is studied experimentally and numerically. laboratory experiments were conducted to record water surface ele...

A large amount of accurate river cross-section data is indispensable for predicting river stages. However, the measured river cross-section data are usually sparse in the transverse direction at each cross-section as well as in the longitudinal direction along the river channel. This study presents three algorithms to resample the river cross-section data points in both the transverse and longi...