Inviscid fluid flow past a square cylinder.

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The discussion focuses on the challenges of simulating inviscid fluid flow around a square cylinder, contrasting it with the well-studied circular cylinder flow. Issues arise due to sharp edges at the corners, which may lead to unexpected vortex formation, contradicting the principles of inviscid flow that should not produce rotation. The conversation highlights the nonphysical nature of infinite acceleration at sharp corners, rendering true inviscid flow around such geometries problematic. Additionally, simulations often require damping to converge, preventing them from accurately representing inviscid conditions. The interest in this topic stems from its theoretical implications, despite its distance from practical fluid dynamics scenarios.
tarnhelm
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The flow of an inviscid incompressible fluid around a circular cylinder is commonly studied in fluid dynamics courses. There's a wikipedia article about it here: http://en.wikipedia.org/wiki/Potential_flow_around_a_circular_cylinder.

However, what about a square cylinder? There seem to be issues with simulating such flow across sharp edges or boundaries like the corners of squares. Can somebody tell me what you expect with such a scenario?
 
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Actually a colleague of mine is about to publish a paper in the Journal of Fluid Mechanics on the viscous flow past a square cylinder. It is a very similar flow field to a circular cylinder but te vortex shedding is more complex. I'd say keep an eye on JFM for it, but it will probably be a year before it is actually published.
 
Thanks for that. I think there's a lot of stuff out there about viscous flow past a square cylinder. However, inviscid flow presents a problem because it may be the case that vortices are produced at the corners, which I don't think should be the case in inviscid flow. At the very least, finite difference simulations seem to produce this effect. As I understand it, steady incompressible inviscid flow shouldn't spontaneously develop rotation like this. I'm wondering if anybody has any more info about it, because google isn't turning up much!
 
The problem is that a truly inviscid flow can turn around an arbitrarily sharp corner, which causes infinite acceleration of the fluid. This is clearly nonphysical. There isn't really a solution to this, which is why it is mostly ignored. If you decide to allow infinite acceleration, it would be qualitatively similar to the circular cylinder in terms of streamlines, but the corners would effectively be singularities in the flow. As for simulations, they have to have some inherent damping in order to converge, so they will never simulate truly inviscid flow.

Out of curiosity, why the interest in inviscid flow around corners? It's quite far from any physically realizable flow.
 
A square cylinder? Someone will have to explain what that means to me.
 

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