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CFD Software

Algorithm Explanation

SIMPLE / SIMPLEC
About underrelaxation of pressure in SIMPLE algorithm

Custom Codes

Schemes

SMART (bounded QUICK) scheme

Solvers

Steady-state PISO solver for compressible flow
Steady-state SIMPLER solver for compressible flow
(modified version)
Another steady-state SIMPLE solver for compressible flow
Incompressible Local Time-Stepping Pimple solver

Turbulence Models

Mut Wall function for SA model

Wall function for nuTilda
Negative Spalart Allmaras model (SA-neg)
Compressibility Correction for Spalart Allmaras model (SA-CC)
Spalart-Shur Correction for Spalart Allmaras model (SA-RC)
Simpler Rotation/Curvature Correction for Spalart Allmaras model (SA-RCM)
Vorticity Source Term for Menter SST model (SST-V)

Others

Calculation of force and moment by porous effect (foam-extend-3.2)

Memo

Decomposition method issue

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About me

Contact

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Links for Perrinn Project

Perrinn.com
Perrinn F1 Onshape
Perrinn F1 2016 Onshape
Perrinn LMP1 Onshape

My GitHub

hf-foam-4.0 repository
Negative Spalart Allmaras Model
incompressible SST-V turbulence model
VONOS div scheme
Wall Function of Turbulence Viscosity Derived from SA model

Popular Posts

SIMPLEC Algorithm of OpenFOAM

1. SIMPLE Algorithm Governing equations can be written as follows using Rhie-Chow interpolation. In OpenFOAM, Eq.(1-2) are written as follows. Step.1: Solve Eqn.(1') implicitly by p* = p0 (p of previous time) and obtain U* Step.2: From continuity equation (div(U) = 0) and Eqn.(3-4), Eqn.(5) can be obtained. Here, an approximation (Eqn.(6)) was used. Step.3: Solve Eqn.(5) implicitly and obtain p. Step.4: Correct U using Eqn.(1'-2'), Eqn.(3-4) and Eqn.(6). Step.5: Go to next time and repeat from Step.1 if not converged. 2. SIMPLEC Algorithm In SIMPLEC Algorithm, the following approximation is used instead of Eqn.(6). In OpenFOAM's expression, Here we can obtain Eqn.(8) from Eqn.(2''). Step.1: Same as SIMPLE Algorithm. Step.2: From continuity equation (div(U) = 0), Eqn.(3-4) and Eqn.(8), Eqn.(5') can be obtained. Step.3: Solve Eqn.(5') implicitly and obtain p. Step.4: Correct U using Eqn.(1'),

CFD for Halo of Formula 1

1. Overview I was curious about what halo does in aerodynamics of an F1 car. In this article, I will show the results of CFD simulations of an F1 car, one is without a halo, and the other is with a halo. 2. Halo The halo was desigined using the following document. https://www.fia.com/sites/default/files/fia_standard_8869-2018_afp_v1_0.pdf Perrinn F1 V13 was used as the car, which was designed according to the 2017 F1 technical regulations. 3. Simulation Setup Wind Speed: 50 m/s Ride Height: 20mm/50mm (Front/Rear) Solver: foam-extend-3.2 steady-state solver Turbulence Model: Spalart Allmaras (+Rotation/Curvature Correction) 4. Forces SCd = Frontal Area × Drag Coefficient SCl = Frontal Area × Lift Coefficient L/D = SCl / SCd FrDF% = Front Downforce / Downforce SCl_F = Frontal Area × Front Lift Coefficient SCl_R = Frontal Area × Rear Lift Coefficient Mass = Mass Flow Rate Passing Through Rad

Meshing with foamyHexMesh

foamyHexMesh is a new mesh generator added in OpenFOAM 2.3.0. In this post, I tried foamyHexMesh for simple shapes (a box and a sphere). Thinking of foamyHexMesh as a meshing tool for air-flow simulations about a car, I created the box as the computational domain which has inlet and outlet, and the sphere as a substitute of a car. Box Sphere I exported these shapes as STL files. Box.stl is separated into 4 parts (inlet, outlet, side, and ground). The diagonal points of the box is (-1, -1, 0) and (1, 1, 1). And the center of the sphere is (0, 0, 0) and the radius of the sphere is 0.5. Box.stl Sphere.stl Here are the steps of using foamyHexMesh. 1. Modify orientations of the faces of STL files at first $ surfaceOrient constant/triSurface/Sphere.stl -inside '(-0.9 0 0.1)' constant/triSurface/Sphere.stl $ surfaceOrient constant/triSurface/Box.stl -inside '(-0.9 0 0.1)' constant/triSurface/Box.stl 2. Create intersections of th

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