Know Thy Solver – Part III: Pressure Equation Methodologies for Incompressible Flow

On December 25, 2018December 25, 2018 By Tomer Avraham ☇Leave a comment

In compressible flows the continuity equation can be used to determinethe density and the pressure can be calculated from an equation of state. This approach is not appropriate for incompressible or low Mach number flows. When considering the incompressibility assumption as valid, Navier-Stokes equations supplemented by continuity take the following recognizable form (body forces neglected): …

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Law of the Wall

On October 30, 2018March 14, 2019 By Tomer Avraham ☇1 Comment

We begin our discussion by noting that there are three quite general and distinct types of turbulent flows: namely, Homogeneous and/or isotropic turbulence, free shear flows and wall-bounded shear flows. Homogeneous and/or Isotropic Turbulence Homogeneous turbulence is such that statistics are invariant under spatial translations, while isotropic turbulence is invariant under rotations and reflections. As rotations and reflections can …

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The Prince of RANS: k-ω SST Turbulence Model

On August 26, 2018November 20, 2018 By Tomer Avraham ☇15 Comments

"Every mathematician believes that he is ahead of the others. The reason none state this belief in public is because they are intelligent people" - Andrey Kolmogorov Most of nowadays CFD simulations are conducted with the Reynolds Averaging approach. Reynolds-Averaged Navier-Stokes (RANS) simulation is based on the Reynolds decomposition according to which a flow variable …

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Going Hybrid

On August 22, 2018November 22, 2018 By Tomer Avraham ☇Leave a comment

Nothing is as beneficiary for the flight industry as the ability to cut substantially on fuel budget. From a CFD perspective, such a goal could potentially be achieved by high fidelity simulation for a detailed design full airborne vehicle . A naive approach for the highest physical fidelity could be a Direct Numerical Simulation (DNS) of Navier-Stokes equations. …

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Meshing Guidance – Fluent

On July 1, 2018July 30, 2018 By Tomer Avraham ☇Leave a comment

The following are some helpful video tutorials designed on giving the user some guidance in Fluent meshing: How to create a CFD mesh using Fluent meshing ANSYS Fluent meshing objects and zones management and display tools Conformal conjugate heat transfer (CHT) meshes in ANSYS Fluent meshing Object-based surface mesh preparation …

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Know Thy Solver- PART II: Projection Methods

On June 25, 2018June 25, 2018 By Tomer Avraham ☇Leave a comment

Hopefully upon finishing reading Know Thy Solver- PART I, we have consolidated the logic and motivation behind NSE solver segregated algorithms. Our task now is to present an important cornerstone which serves as a building block for ANSYS Fluent pressure-based algorithms as in most other commercial CFD codes - Projection Methods. It is important to note …

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Know Thy Solver- PART I: Introduction to NSE Algorithms

On May 17, 2018December 25, 2018 By Tomer Avraham ☇Leave a comment

A successful CFD analysis workflow consists of the following key elements (sometimes by repeating cycles, and sometimes with additional elements as-per-cause): Definition CFD modeling goals according to the model problem at hand: Physics gives us a description of reality or in other words, a model, by such CFD modeling goals should conform to the level …

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