# Tag Info

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Back in August 2011, I followed a beginners course on LBM in Canada. The resources for that course are still up and contain a nice tutorial covering a wide range of topics: theory, coding setup, boundary conditions, multiphase, etc. The simpler tutorials are in Matlab, for the more advanced tutorials some knowledge of C/C++ is required. To be frank if you ...

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First, I'm not sure why you emphasize on water? I mean I understand that you are looking for a CFD scheme that works for your special case, but you need to know that water fluid is not a special fluid at all. Water is a incompressible fluid and you can simulate its movement by using incompressible Navier-Stokes equation as long as your Mach number is not ...

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The Lattice Boltzmann is not a meshless method. Actually, when looking at it, it is a finite difference method on an homogenous structured Cartesian grid (dx = dy = dz). However, the variables solved for are not the primary variables (U and P), but are pseudo-populations $f_i$ where $i\in [1,n_p]$ and where $n_p$ is the number of population in the lattices....

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I believe this paper by Breuer et al. which uses both the lattice Boltzmann and the finite volume method could be of interest for you. There is tremendous information therein and I have used it before as a benchmark. I am not sure if it is THE reference, but it is a good one (and cited above 300 times) http://www.sciencedirect.com/science/article/pii/...

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The GPU consists of several streaming multiprocessors. Each SM has 64-96kB of shared memory that can be accessed by up to 1024-2048 threads. This shared memory allows these threads to communicate. To communicate between SMs you must write to and read from the GPU's global memory, which is 4-32GB in size. But it is best to think of your problem as consisting ...

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In my opinion issues in LBM like this almost always relate to the boundary condition implementation. Depending on the choice of BC and the way it is implemented it can deteriorate the accuracy of LBM from $O(\delta^2)$ (second-order) to $O(\delta^{1.5})$ or worse to $O(\delta)$ (first-order). I am not familiar with the specifics of the BFL condition but if I ...

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Generally, the viscosity we speak about (which is linked to the relax. time) is the kinematic viscosity $\nu$, not $\mu$ as you write. So, by replacing, you will find the right expression.

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I think that both can be considered to be equally valid. In fact, asymptotically (with an infinite number of lattice) you will tend towards the incompressible athermal Navier-Stokes equations. In this limit, both measures of the flow should be equal. If I were you, I would initially report the two. Then I would measure the difference between them as a ...

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I disagree with the answer given by Alone Programmer. His reasoning is not objective and seems to be based on a very primitive lattice-Boltzmann model with BGK collision operator. LBM has significantly matured over the years and is in my opinion a very attractive numerical solver. Nonetheless it depends on the application if it really fits your needs. I ...

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Your outlet boundary condition is not correct. In your outlet BCs, you have to impose the value of $f_6$, $f_3$ and $f_7$ since these populations are not updated by the streaming step. This paper presents a good example on how to do an outflow BC in LBM : https://www.researchgate.net/publication/...

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In (1), $f$ is an unknown function of $t$, $x$ and $\xi$. Here $\xi$ denotes the moment of a particle. Note that (1) is only a scalar equation for $f=f(t,x,\xi)$. From (1) to (2), we actually discretize the space of $\xi$, from continuous space $-\infty<\xi<\infty$ to discretize space $\xi_1$, $\xi_2$, $\dots$, $\xi_n$. Now (2) is a set of $n$ ...

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You can go check the book 'The Lattice Boltzmann method: Principles and Practice' In chapter 2.4 - Outlook: Why Lattice Boltzmann?, it talks about the simplicity, efficiency, geometry and the applications in multiphase and multicomponent flows, thermal flow, sound wave, and compressible flow. It might not appropriate to copy and paste them here. So I would ...

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Each method has its pros and cons. LBM ans NS solvers are both efficient and reliable. The no-slip condition may be important for physical meanings, otherwise it may be enough for you to solve Euler's equations (inviscid fluid), depending on your needs. Since you mentioned vorticity, the Navier-Stokes equation can be written in a velocity-vorticity ...

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Unless you use specific boundary conditions like an immersed boundary method, the gray part does not exist for the computation after the boundary nodes have been selected. As far as the computation goes, black nodes represent the wall and no other wall exists. Blue nodes have all degrees of freedom. If you use D2Q9, all 9 propagation directions are used, so ...

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