Rhys Ulerich
  • Member for 10 years, 1 month
  • Last seen more than 1 year ago
Looking for analytic solutions to time dependent fluid flow problems
5 votes

Try looking into the solutions available within MASA. MASA is a library of manufactured solutions containing many steady and transient problems for the flow physics you describe. These don't tend to ...

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Fourier pseudo-spectral method and numerical dissipation
5 votes

Understanding what the dealiasing does requires understanding why you're taking FFTs in the first place. For me, the method of weighted residuals approach provides the simplest framework: You're ...

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What programming language should I choose and why?
4 votes

Learn 2. Likely Python and (C++ or Fortran). Learn how to integrate them, for example writing orchestration/loading/analysis in Python and compute kernels that matter for performance in the other ...

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Nondimensional gas constants
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4 votes

If you are using an ideal gas equation of state, only the ratio of specific heats should appear in the nondimensional governing compressible Navier-Stokes equations. Knowing that you want to simulate ...

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Euler equations in 2d
4 votes

Yes, the 2D problem more-or-less becomes solving a 1D problem in the X direction followed by a 1D problem in the Y direction. The data structures are a little more complicated, the Roe matrix needs ...

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How are Spectral Methods applied to CFD? In particular, how is the pressure-velocity coupling implemented?
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3 votes

For incompressible spectral DNS, often you'll see reference to John Kim, Parviz Moin and Robert Moser (1987): Turbulence statistics in fully developed channel flow at low Reynolds number, Journal of ...

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What Is The Intersection Between CFD and Computer Science
3 votes

Re: The Intersection... There's a ton. But a great CFD guy might not offhandedly know basic DAG traversal. And a great CS guy might not offhandedly know about the practical tradeoffs inherent in ...

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Computing Kolmogorov/Energy spectrum for turbulent boundary layer
3 votes

1) One usually chooses one or two representative wall-normal distances and presents the spectra for <u'u'>, <v'v'>, etc. over the homogeneous directions. For example, see Figure 11 within ...

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Estimating the Courant number for the Navier-Stokes Equations under differing Reynolds number regimes
3 votes

If you're looking for a time step stability criterion in the nondimensional compressible Navier--Stokes setting, Guarini derives an estimate of it using scalar stability theory in section 4.2.2 of his ...

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2d pseudo-spectral turbulence simulation with random initial velocities
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2 votes

Goofy question, are you dealiasing in some fashion or is it unnecessary in your setup? The issue sounds convective in some sense otherwise I'd expect your diffusion dominated limit to misbehave. If ...

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How can I choose a good Riemann solver when numerically solving a system of hyperbolic PDEs?
2 votes

I've been lead to believe that for low order numerics one needs high quality Riemann solvers and for high order numerics one can use low quality Riemann solvers. Intuitively there's some number of ...

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Adding artificial fluctuations to trigger hydrodynamic instabilities.
1 votes

The Gaussian is annoying to add since it isn't compactly supported. The bump function solves that but has nasty higher derivatives that require resolution. I spent a little time once figuring how to ...

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C - OpenMP, MPI, Serial Program
1 votes

Something in your description sounds amiss when you say you need four codes. You may want clarification from your instructor. Would one MPI+OpenMP code that produces correct results for any "...

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Euler's equations 1d for pipe, Inlet boundary conditions
1 votes

I lack the time to dig into it at the moment (sorry), but any chance sections 2.9, 2.10, and 2.11 from Liepmann and Roshko (available in the linked Amazon preview) can help resolve your question? The ...

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Confusion Over Navier-Stokes, RANS and URANS in a Flow With Laminar-Turbulent Transition
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1 votes

You are solving the RANS equations. It just so happens that people apply the RANS equations so often to steady problems that people inexplicably think of URANS as some different beast. It's not. You ...

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When is a high order method useful for computational fluid dynamics simulations?
1 votes

Always implement at least two distinct orders. On a representative problem, solve once using each order. Compare the two on a grid fine enough to be converged at the lower order. Ensure your two ...

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