Learning Forum

[soloviev]

Hello,

We run various models which are simulated in open ocean conditions. We also run the MHD model in many of these. We are curious as to which boundary conditions in the MHD model are the best to use for these. We do not really have walls, since the box containing the water in which we are modeling is just meant to be a segment of the open ocean. We know there are insulating, conducting, coupled, and thin wall boundaries, but which would be most accurate for what we are modeling?

 

Thanks,

Alex

[Rob]

I suppose the correct answer is "it depends". Typically flow is going somewhere so we have inlets/outlets. If there isn't any flow and the boundaries are a long way from the area of interest then isothermal walls may work? You'll have to give us more information! 

[soloviev]

We do have inlets and outlets, sometimes periodic boundaries at them depending on the model. We are just wondering which in the MHD to use to accurately model the magnetic signal as if it were open ocean conditions. We have done models with insulating and conducting but the results are dramatically different, and aren't sure which would be more accurate. 

[Rob]

Assuming the signal is supposed to pass through the boundary I'd assume you want something that will absorb or be invisible to the magnetic field. Not something I can advise on: it's an area I don't really understand. 

[soloviev]

Yes, we are looking for something essentially invisible to the magnetic field.

Is there another topic area we could post in to get some suggestions?

Thanks,
Alex

[soloviev]

Hello,

 

Is there any update to this issue?

 

Thanks,
Alex

[Dilini]

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Hello,

wondering if a solution came up for this problem. I am modeling a coastal ocean setting. I tried using a pressure outlet with the hydrostatic pressure distribution for the offshore boundary, but it did not give realistic results (and it gave reversed flow). I cannot use a wall here since I need a representation of the open ocean extending from here. Any help is appreciated.

Thank you.

.

[Rob]

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Ocean modelling is a little beyond CFD, not because we can't do it but because no-one knows the boundary conditions. Open channel is your best option if you're modelling the free surface or if not pressure boundary, but make sure the operating density is set for the "outside" temperature.

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