The study of the properties of fluids and gases in motion

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Plot temp Vs time on ansys fluent

I have simulated a transit case by using ansys fluent. How can plot temp vs simulated time?
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1answer
39 views

Zero-k mode in Pseudo-spectral solution of Stokes Flow

I'm trying to solve a Stokes flow problem with a pseudo-spectral method in periodic boundary conditions. The equations of interest are $-\nabla^2 \bf{v} + \nabla p = \bf{f} \\ \nabla \cdot \bf{v} = ...
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33 views

ENO/WENO component-wise vs characteristic-wise

Can someone give some references to understand what's the differences between a component-wise and a characteristic-wise ENO scheme? If I'm right, the characteristic variables come from the ...
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2answers
70 views

Expected computational time for DNS computation of fluid flow

Using an established criterion involving capturing eddies down to the Kolmogorov length scale it can be reasoned that the order of grid points in the computational mesh needs to be $N^3 \ge Re^{9/4}$ ...
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1answer
124 views

Finite Element integration with tensor notation

While I was studying discontinuous finite element methods I found an integration of a Navier Stokes equation using tensorial notation. The equation is the following: $\mathbf{\bar {u}}_{t} + ...
2
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0answers
80 views

Finite Volume/difference scheme for 2d continuity equation

I am trying to solve the following 2D continuity equation on the rectangular domain [0,1]x[0,1] using the finite volume method. $\rho_t + \nabla \cdot (\rho v) = 0$ where the velocity $v =(v1,v2)$ is ...
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3answers
92 views

What Is The Intersection Between CFD and Computer Science

What Is The Intersection Between CFD and Computer Science... And.. How hard would it be to undertake a PHD in CFDs after an undergrad and masters in CompSci Many Thanks....
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2answers
82 views

Can the conservative form of the advection equation be re-written by replacing the velocity term with an integral over all other points in space?

Suppose I have a 1D advection equation in conservation (divergence) form $\partial_t u(x,t) = -\partial_x [v(x)u(x,t)],$ where $u$ is a conserved quantity in space, and $v$ gives the velocity of the ...
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29 views

Comsol - Make an stl file a domain for CFD

I need to do a CFD simulation with Comsol. I have an STL file with a mesh describing the surface of an object on which I would like to do some fluid dynamics simulation. As far as my understanding ...
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1answer
62 views

Finite Volume Method flux integration

I was reading through this document about FVM. I understood all up to the point where we have on page 15 the following $$(\bar u^{n+1}_i - \bar u^n_i) \Delta x + \int^{t^{n+1}}_{t^n} ...
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1answer
109 views

What kind of test cases are convenient to use for testing the code for Euler equations of gas dynamics in polar coordinates?

Consider Euler equation of gas dynamics in polar coordinates as $$ \left( \begin{array}{ccc} \rho \\ \rho u_{r} \\ \rho u_{\theta} \\ E \end{array} \right)_{t} + \frac{1}{r} \left( ...
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1answer
59 views

CFD: Mesh problem [closed]

I wish to study the 2D heat transfer of the soda can using Fluent. For my geometry I took a circle. My problem while meshing the circle; Because i need to mesh it from inside. I used the mapped faced ...
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74 views

Two Dimensional Nozzle Flow

I've been looking at the book "Computational Fluid Dynamics - The Basics With Applications", by John D. Anderson, and his solution for the one-dimensional subsonic-supersonic nozzle flow using the ...
2
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1answer
61 views

Trignometric/Fourier spectral collocation with zero Dirichlet BC in 2D

I am concerned with numerical solution to the following problem on $[0,1]\times[0,1]$. $\dfrac{\partial\theta}{\partial t}+u(x,t).\nabla \theta(x,t)=\kappa \nabla^2\theta(t,x)$ with Dirichlet ...
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2answers
92 views

Fluent time step size (transient implicit solver)

I am studying fluid-structure interaction across integrated circuits packaging by using Ansys Fluent (I'm a beginner). Currently I had an issue about the time step size. When I set time step size of ...
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0answers
58 views

Euler Equation Eigensystem with Gravity in the Energy Flux

I am modifying a conservative form of the Euler equations with gravity in the energy flux (see previous question: Energy Conservation in Conservation Laws with Source Terms) for use in a Riemann ...
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21 views

LBM for thermal anlysis

Can Lattice-Boltzmann methods be used for thermal analysis of radiation or conduction? (Hints for papers and libraries are highly appreciated.)
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2answers
119 views

How to set up a shock tube problem such that the solution includes a shock with a specified Mach number

One of the famous and convenient test cases for shock wave modeling is the 1D Sod's shock tube. This is a Riemann problem for the compressible Euler equations of gas dynamics. The initial set up has ...
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138 views

Test Case with Known Solution for 3D Navier Stokes Equations

Is there a test case for 3D incompressible Navier Stokes Equations like the Taylor vortex in two dimensions? I know, I can easily construct 3D manufactured solutions but I would like to have ...
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2answers
72 views

Nondimensional gas constants

I am doing a nondimensional Navier-Stokes simulation, but it's not exactly clear what values to use for the various gas constants: $R$, $C_v$, and $C_p$. Obviously, once I know one of these and ...
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0answers
34 views

Compute drag force on a mesh in SU2 CFD (beginner) [closed]

I am a complete beginner in computational fluid dynamics. I have a 3D mesh in Blender representing the object I would like to do my tests on. I can export it in (I think) any useful format for 3D. I ...
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13 views

Convergence criterion for overset grids

If there are two overset grids, how do you decide whether convergence is reached or not? What I did was, after interpolating from one grid to another, I check the rms of conservative variables and if ...
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2answers
267 views

What are the differences between CFD simulations and realistic ocean/atmosphere model simulations?

The field of computational fluid dynamics (CFD) is dedicated to solving the Navier-Stokes equations (or some simplification of them). A subset of CFD, ocean and atmospheric models numerically solve ...
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1answer
67 views

Deriving entropy function and entropy flux for a system of equations

I've been reading up on the concept of entropy as a useful way of developing a natural residual for a system of equations. For example, the entropy function for compressible Navier-Stokes is ...
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1answer
148 views

Energy Conservation in Conservation Laws with Source Terms

I'm wondering if anyone can help me understand energy conservation when using conservation law methods (i.e. Riemann solver, High-Resolution Wave-Propagation Methods) with the addition of source ...
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1answer
240 views

Patankar's algorithms for Numerical Heat Transfer and Fluid Flow

I am looking for the algorithm of Patankar (for example, SIMPLE, SIMPLER, SIMPLEC and PISO) written in Fortran for the simulation of heat transfer and fluid flow.
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62 views

jump conditions for Poisson/Darcy equation in primal form versus mixed form

Consider the Darcy equation, $$\mathbf{v} + \dfrac{k}{\mu_0}\nabla p = \mathbf{f} \\ \mathrm{div}\; \mathbf{v} = 0$$ If the coefficient $k$ is piecewise constant across an interface $\Gamma$ in the ...
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138 views

Is there a jump condition for this PDE? ( Brinkman model , piecewise constant permeability)

The Brinkman equations for steady flow of an incompressible fluid through rigid porous solid are: $-\dfrac{\mu_0}{k}\mathbf{v} - \mathrm{grad}p + \mu_0 \Delta \mathbf{v} =0$ and ...
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2answers
79 views

Simulating interaction of Smart Fluids with Solids

Is it possible to simulate interaction of Smart Fluids with Solids? Is there a software capable of doing so? What I Know: The two software that I know of are Autodesk Simulation Mechanical and ...
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85 views

How to get proper parameters of SPH simulation?

I'm implementing basic fluid flow simulator using SPH method basing on e.g. https://www10.informatik.uni-erlangen.de/Publications/Theses/2010/Staubach_BA10.pdf. So far I've implemented: uniform ...
4
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2answers
183 views

Projection Method: Boundary condition on intermediate velocity field

I'm trying to solve variable density and viscosity Navier-Stokes equation using lagged pressure projection method. I'm solving for cavity problem as a test case now (once I get projection right, I ...
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1answer
53 views

FEM with soil slope

I what to calculate displacements, stress and strain in a soil slope with a FEM script. The slope moves like a laminar flow. Can you suggest me some bibliography on this problem? I've already look on ...
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1answer
148 views

Finite Elements Weak Formulation generalization

I am struggling with an equation that represents the Weak form of Galerkin method: $ \phi^{T}F(\textbf{u})\sim \int_{\Omega}^{ } \phi.f_{0}(\mathit{u},\nabla \mathit{u}) + ...
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1answer
167 views

Organizing a CFD program written in python

I've spent some time writing a spectral element solver aimed at solving fluid flow problems concerning the motion of self-propelled bodies. I've gotten to the point where the code has grown long ...
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3answers
154 views

vector PDEs on manifolds

What are the subtleties involved in solving vector PDEs on manifolds? Can someone suggest a reference summarizing the problems involved? Specifically I want to solve a vector Helmholtz equation with ...
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2answers
217 views

CFD absractions in Modern Fortran

I'm a novice in object-oriented programming, but this design technique seems very interesting for me. I have a Fortran 90 CFD package , not very complex, but it is already very hard to maintain and to ...
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1answer
255 views

MPI_ERR_TRUNCATE appears for no understandable reason

I am developing some parallel CFD code using Fortran 90 and OpenMPI. The processes are structured into two groups such that half perform a certain type of calculations (let's say Velocity, Pressure ...
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1answer
80 views

Importance of change the Time Step Value for the Accuracy of a Transient CFD Simulation

I have a transient simulation for a case from 0 to 3 sec , actually i interest the solutions on time range from 2 to 3 sec , as my velocity and mesh size , my time step should be 0.0000000001 sec , my ...
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2answers
158 views

C - OpenMP, MPI, Serial Program

I'm part of a Computational Science course and come from a non-programming background, so please forgive me my ignorance. I'm working on a set of code in C to numerically solve the Navier Stokes ...
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32 views

Tecplot Span-Wise Loading Visualization

all. I have data from a CFD simulation for a wing, and I need to obtain a visualization of the span-wise load distribution. I'm attempting to do this using Tecplot. I've tried using 'slices' and ...
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1answer
118 views

Type of Navier-Stokes equation

What type equation Navier-Stokes is: Elliptic, parabolic, or hyperbolic? Should it give always the same answer no matter what is the initial condition? How these statements could be proved?
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1answer
58 views

Regarding streaming operator in Lattice Gas Automata

The classical streaming operator used in FHP lattice gas automata is this: $$n_i(r - c_i, t + 1) = n_i(r, t)$$ However if you think in terms of the streaming itself, it should be something like ...
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3answers
173 views

Solving Stokes flow with walls using Oseen tensor

Introduction I've developed a code to solve for generalised, incompressible 2D Stokes flow $\eta \nabla^2 \mathbf{v} - \nabla p + \mathbf{S} = 0$ $\nabla . \mathbf{v} = 0$ where $\mathbf{S}$ can ...
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3answers
153 views

How to get discretization coefficients of matrix A in Finite Volume Method (FVM)?

First we have Discretization of the Transport Equation $$ \frac{\partial \rho \phi}{\partial t} + \nabla(\rho U \phi) - \nabla (\rho \Gamma_\phi \nabla \phi) = S_\phi (\phi) $$ In Finite Volume ...
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4answers
149 views

What scale problem can be simulated on an PC using Smooth Particle Hydrodynamics?

I want to simulate tidal features in a large body of water using was smooth particle hydrodynamics. For a system composed of an incompressible fluid, what general scale of problem can be tackled with ...
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2answers
136 views

What makes turbomachinery so special in CFD

As my experience with CFD grows, I start to gain the feeling that turbomacinery is kind of special in CFD: there are special tools tailor for it. For example, ANSYS has TurboGrid or Vista TF for ...
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211 views

Do black-box preconditioners for matrix-free methods exist?

Jacobian-Free Newton-Krylov (JFNK) methods, and Krylov methods in general, can be very useful because they don't require explicit storage or construction of a matrix, only the results of matrix-vector ...
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1answer
268 views

Comparison of Lattice Boltzmann Method vs Traditional Navier-Stokes based Methods

I have a choice of two options, analysing and implementing Lattice Boltzmann methods or traditional Navier Stokes based methods. I'm a CFD newbie and I have a rough idea (though not rigorous enough to ...
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1answer
102 views

Is it possible to simulate fluid dynamics in a time-based and deterministic manner?

The Problem Domain I have a number of network-connected PCs. I want to be able to simulate and replicate the same simple fluid dynamics simulation (E.g. Navier-Stokes), in real-time, between them. ...
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1answer
175 views

Moving airfoil boundary conditions

I am trying to simulate a moving airfoil with constant speed (Mach=0.755, aoa=1.25). I solve Euler equations with Roe's method. I have two boundary conditions: Farfield Slip wall (airfoil) For all ...