We present a straightforward method to solve gas damping problems for perforated structures in two dimensions (2D) utilising a Perforation Profile Reynolds (PPR) solver. The PPR equation is an extended Reynolds equation that includes additional terms modelling the leakage flow through the perforations, and variable diffusivity and compressibility profiles. The solution method consists of two ph...

The effectiveness of five different turbulence models is assessed for the flow across a row of confined cylinders at a pitch-to-diameter ratio of 1.7 and at Reynolds numbers ranging from 2621 to 55 920. Models examined include the one-equation Spalart-Almaras model; twoequation realizable k «, k v, and shear stress transport models; and a four-equation v2 f model. Quantities compared against pu...

This report presents an evaluation of the steady-state capability of the turbulence models available in the commercial CFD code FLUENT 6.0, for their application to the simulation of hydrofoil turbulent boundary layer separation at high-Reynolds numbers. Four widely applied two-equation RANS turbulence models were qualitatively and quantitatively assessed through comparison with high-quality ex...

The main topic of the presented paper concerns the method of determination and calculations of the general and particular numerical solutions of modified Reynolds equation in curvilinear orthogonal coordinates for curvilinear boundary conditions for hydrodynamic pressure distributions in bearing gap. A general solution matrix was derived and determined for various orthogonal coordinates of two ...

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We describe a method to compute veriied enclosures for solutions of the stationary Navier-Stokes equation in two-dimensional bounded domains. In order to obtain error bounds for numerical approximations , we use the theorem of Newton{Kantorovich. Therefore, we compute approximations for the stream function of the ow and upper bounds of the defect in H ?2 (); we determine an upper bound for the ...

The thin film pressure balance (TFPB) technique was used to study the kinetics of film thinning in the presence of sodium dodecyl sulfate (SDS) and sodium chloride (NaCl). The experimental results were compared with the predictions of the Reynolds equation. During the initial stages, the film thinning was controlled by the capillary pressure. As the film thickness is reduced, the process is con...

The accurate modelling of damping is essential to capture the dynamic behaviour of a MEMS device. Our interest lies in squeeze-film damping which models the behaviour of a fluid in small gaps between a fixed surface and a structure moving perpendicular to this surface (Fig.1). The lateral dimensions of the surfaces are large compared to the gap and the system is considered isothermal. Squeeze f...

In this paper we discuss recent progress in using the Camassa-Holm equations to model turbulent flows. The Camassa-Holm equations, given their special geometric and physical properties, appear particularly well suited for studying turbulent flows. We identify the steady solution of the Camassa-Holm equation with the mean flow of the Reynolds equation and compare the results with empirical data ...