Large-eddy simulations of incompressible Newtonian fluid flows with approximate deconvolution models based on the van Cittert method are reported. The Legendre spectral element method is used for the spatial discretization to solve the filtered Navier–Stokes equations. A novel variant of approximate deconvolution models blended with a mixed scale model using a dynamic evaluation of the subgridv...

A self-adaptive dissipation method based on a fifth-order dissipative compact scheme is proposed to reduce the numerical in separated flow. The involves operating parameter adjust weight of upwind part, which major source dissipation. Cooperated with delayed detached eddy simulation, can perform less large-eddy simulation region resolve more small-scale structures, and return normal Reynolds-av...

Here hi = uiφ − ūiφ̄ is the SGS scalar flux. Both τij and hi are not available from the resolved (LES) flow field and thus have to be modeled. A very promising approach to modeling τij and hi consists of utilization of extra LES quantities such as SGS kinetic energy (Schumann 1975; Ghosal et al. 1995) and SGS scalar variance (Jiménez et al. 2001; Chumakov & Rutland 2004, 2005). For these quantit...

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The spectral vanishing viscosity (SVV) method has recently appeared of interest for the large-eddy simulation (LES) of turbulent flows. Here we show that the SVV-LES approach allows to easily compute turbulent quantities, like the dissipation rates of the turbulent kinetic energy or of the variance of a passive scalar and to clearly discern the subgrid and viscous contributions. Results obtaine...

Wind and temperature observations in the mesosphere and lower thermosphere (MLT) from the Upper Atmosphere Research Satellite (UARS) reveal strong seasonal variations of tides, a dominant component of the MLT dynamics. Simulations with the Spectral mesosphere/lower thermosphere model (SMLTM) for equinox and solstice conditions are presented and compared with the observations. The diurnal tide i...

A perfect modeling framework for the systematic study of the effect of filter shape on the resolved scales of motion in large eddy simulation is developed. The effects of the explicit and implicit filtering approaches in large eddy simulation are considered. A simple model for smooth filtering is proposed and the related effects are analyzed. The proposed approach provides an effective research...

recently the stepped spillways have been used as an appropriate solution for energy dissipation. in the present study, siahbisheh dam spillway is simulated by using computational fluid dynamic (cfd), in which the mixture method and reynolds stresses model (rsm) turbulence model is used. in the first modeling series the over all steppes slope is constant. the number of the steps is increased to ...

The performance of a subgrid stress SGS model for large eddy simulation LES developed by Misra Pullin is studied for forced and decaying isotropic turbulence on a grid The physical viability of the model assumptions are tested using DNS databases The results from LES of forced turbulence at Tay lor Reynolds number R are compared with ltered DNS elds Probability density functions pdfs of the sub...

Accurate modeling of heat dissipation in pediatric intracorporeal devices is crucial in avoiding tissue and blood thermotrauma. Thermal models of new Maglev ventricular assist device (VAD) concepts for the PediaFlow VAD are developed by incorporating empirical heat transfer equations with thermal finite element analysis (FEA). The models assume three main sources of waste heat generation: coppe...