Hi all,
I'm planning to simulate flow past a floating body using CFD method with the main purpose of investigating its stability against hydrodynamic forces. A sketch of the problem is presented the the figure attached.
It seems that an accurate estimation of pressure field, and therefore hydrodynamic forces, is heavily dependent on correct prediction of flow topology, particularly separation and reattachment of the flow.
I'm wondering what turbulent models would best handle this problem. I would appreciate it if you provide details and specific reasoning.
Regards,
Armin
If you are not a CFD expert, I suggest to read first the papers illustrating the forward facing step flow. For example have a look to the search:
https://www.google.com/search?client=firefox-b-d&sxsrf=ALeKk00S0xk9Vacbfv71o-PPbWzehbi_Hw%3A1611938756439&ei=xDsUYIyqGovbkwXfy6g4&q=forward+facing+step+flow&oq=forward+facing+step+flow&gs_lcp=CgZwc3ktYWIQAzIFCAAQywEyBggAEAgQHjIGCAAQCBAeMgYIABAIEB4yBggAEAgQHjoECCMQJzoHCCMQsAIQJzoICAAQCBAHEB46BggAEAcQHjoICAAQBxAeEBM6CggAEAgQBxAeEBNQnGhYx35gqoEBaABwAHgAgAFyiAG8B5IBBDEwLjGYAQCgAQGqAQdnd3Mtd2l6wAEB&sclient=psy-ab&ved=0ahUKEwiMnOjny8HuAhWL7aQKHd8lCgcQ4dUDCAw&uact=5
Hi,
In such cases, it is better to solve the whole boundary layer, so if you use RANS models, it is better to use k-omega model with yplus = 1.
Dear Armin Hajighasem Kashani
Actually, it depends on the velocity and Reynolds number. Speaking of the RANS based turbulence models, K-epsilon suits for high Reynolds number region, whereas K-omega fits with the low Reynolds number regions. The optimal choice could be K-epsilon (developed models) with a low y plus value for the regions where are susceptible to the velocity gradients like sharp edges. You could make use of SST K-W also, but the latter one is much better in terms of stability because the SST K-W model should always switch between K-epsilon and K-w. For your reference please see Sadra Kianejad's papers.
Regards
My opinion is that the original question should be posed in different terms. Befor considering the turbulence model, one should wonder first about the more suitable formulation for this problem, that is considering among DNS/LES/DES, RANS/URANS.
I would second Hamed Majidian, K-epsilon developed models will be preferable choice.
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