![]() NOMENCLATURE Pressure Volume Density ̇ Mass flow rate Flow Rate Viscosity of fluid Area of the boundary Height of lateral gap Angular velocity R Radial Gap Boundary mesh resolution F Force Velocities in the X and Y directions Shear stresses in XY plane the X and Y directions Tilt of the bearing block θ Angular position Vectors: Radius vector Velocity vector Face normal Shear Stress Tensor Torque acting on gear Power losses arising out of the gap are also described considering a detailed description of the gap flow. This combined approach allows a more detailed description of the effects of the lateral and radial lubricating gaps on the operation of the machine. The present work details the procedure developed to implement the coupled approach. ![]() This enables a calculation of the pressure distribution in the lateral lubricating gaps between the gears and the sliding bushings of the external gear machines considering full hydrodynamic lubrication. The CFD model developed is an automatic pre-processor and a finite volume numerical solver of the Reynolds Equation. tooth profile, design of sliding elements) and the movements of the gears" axes of rotation resulting from the forces exerted on both gears. ![]() The tool described is named HYGESim (HYdraulic GEar machines Simulator) it enables detailed modelling of external gear machines, taking into account a lumped parameter fluid dynamic model to simulate the flow through the unit, an accurate description of the geometry of the components (i.e. Overall, the wavelet-based decomposition is a valuable tool to study and reveal the mechanisms of airfoil noise generation.Ī novel approach to couple a Lumped Parameter model and a CFD model to accurately model External Gear machines is described in this paper. Finally, the wavelet transform is used to decompose the hydrodynamic and acoustic pressure components near the surface using the coherence between near-field pressure and far-field pressure. For example, the wavelet method separates noise between low-frequency vortex shedding noise and high-frequency LSB noise as well as trailing-edge noise. In another usage, the wavelet thresholding algorithm with down-sampling separates noise on the basis of flow structures. ![]() It also reveals the dominant noise source at specific frequencies when multiple noise sources are present. This denoising technique provides a clear picture of true noise generation and propagation. The wavelet thresholding and denoising algorithm is used to decompose the pressure fields into the coherent or denoised pressure and the incoherent or background noise pressure. The LSB triggers the flow transition for both the forced and natural transition cases. At a high angle of attack, vortex shedding and a laminar separation bubble (LSB) occur on the suction side. The main contribution of the paper is to show the benefits of employing Julia as a programming language for scientific applications, and Gridap as a Finite Element library, which provided easy access to high performance resources as multi threading, parallel processing, GPU acceleration, thus great versatility in solving complex problems.Īirfoil noise is predicted and analyzed using wall-resolved large-eddy simulations and wavelet transforms for a NACA 0012 airfoil at a Mach number of 0.06 and a Reynolds number of 400,000 using a stair-strip forced transition and a natural transition. The proposed benchmark problem, even addressing a relatively simple geometry and a linear differential equation, has singular regions that cause numerical difficulties, thus limiting the rate of convergence of the numerical approximations. We compared results obtained employing diverse numerical and computational choices, such as variable mesh refinement levels, finite element interpolation order, pre-conditioner classes, and solver configurations (architecture, memory, multi-threading, etc.). As a continued effort, this paper is intended to reproduce results previously obtained of pressure distribution and velocity field, now employing Gridap, a Julia language-based library, able to explore different approaches of approximation Finite Element spaces, and high performance solution strategies. Several numerical simulations of drug release from coronary drug-eluting stents were formerly performed by the authors through Matlab © and Octave to understand transport and binding mechanisms over the device/artery interface.
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