Thank you for this excellent tutorial sir, liked and subscribed.

@MiniUniverse_RA

Жыл бұрын

Happy to hear that

Hi i would like to carry out a similar simulation but for a floating dredge pipe .

Nice! But this only deals with the pressure drag. How can I calculate skin drag as well?

can you show how to do lift and drag coeficient

Thank you, it is a very good example. can you upload the file because i want to know how you generate this geometry and mesh?

@MiniUniverse_RA

2 жыл бұрын

I don't have the exact file of this simulation. But I may have some similar files. If you want, you can send me an e-mail.

i have a question that can i use simpleFoam with the air fluid ? just P and U in file 0

@MiniUniverse_RA

Жыл бұрын

Yes, I thinks so.

I can use points instead cells? In my model doesn’t appear cells

@MiniUniverse_RA

3 жыл бұрын

I don't think so. We compute cell normals but how you can do it? But give it a try.

Do you know how to determine the drag force in a 2D porous cylinder (laminar)? I used the same approach but it didn't work, it's too low.

@MiniUniverse_RA

3 жыл бұрын

in this approach you should have a surface, but for 2d we don't have any surface. Try 3D. There is a way you can calculate drag coefficient in 2d form. But, that is a bit difficult and long. I may make a video about that in future.

@antoine1407

2 жыл бұрын

@@MiniUniverse_RA i need the 2D cass

@MiniUniverse_RA

2 жыл бұрын

@@antoine1407 You can try 2D case, but I'm not sure about results.

I have one question regarding the drag calculation. The drag you are considering, is it only for water flow? Or in the calculation, you also have taken the effect of air? Because I have used the same technique as yours to calculate the drag of DTC Hull. However, the drag I got from your method is -46 N and the built-in force function of OpenFOAM provides -40 N. Therefore, I need some clarification. I will appreciate it if you have time to enlighten the matter. Thanks you.

@MiniUniverse_RA

2 жыл бұрын

It is the pressure and it can be the effect of the water and air (I mean both). But in my case the effect of air is negligible. The difference in your data can be the result of many factors. including mesh grid and etc.

@kawsarsajib8600

2 жыл бұрын

@@MiniUniverse_RA Thank you Sir for the response. I want to provide you a lil bit more information about the case, 1. The result I am showing is from the same simulation. 2. In the built-in case, they also have introduced only water. Question: Is there any way to check in paraview which area has been taken into account to calculate drag? Thank you for your time.

@MiniUniverse_RA

2 жыл бұрын

@@kawsarsajib8600 when you extract block and surface, it means it is the area where the drag is going to be calculated on.

@kawsarsajib8600

2 жыл бұрын

@@MiniUniverse_RA Thanks for your time. Best of luck and hope to watch more demonstrations from you.

You mentioned that we can calculate for all time steps. Is this method for all time steps or just for the 1.1 sec which was selected above ? could you share the process for calculating lift and drag forces for all the time steps ? Thank you, would really appreciate your help.

@MiniUniverse_RA

2 жыл бұрын

Yes, we can do it. You should just select your desired time step then you can continue the process.

@siddheshpujari9140

2 жыл бұрын

But how can we plot all the values of forces for timesteps???

@MiniUniverse_RA

2 жыл бұрын

@@siddheshpujari9140 I looked for it, but I couldnt find a way to do so. I used excel to plot them. I wrote the amount in each time step and then imported them into excel.

Nice, can you provide solver information and case file ?

@MiniUniverse_RA

3 жыл бұрын

The solver is interFoam .There are lots of similar dam break cases in tutorial folder. You can use them.

What are the units for the lift and drag forces ? N/m^2 ? kg/m^2 ?

@MiniUniverse_RA

3 жыл бұрын

The units are in "N"

@nickjohnsonn9761

2 жыл бұрын

​@@MiniUniverse_RA So, it means that if we are in using incompressible solve like "simpleFoam", we should input in the calculator this formula: p*rho*NormalX Unit Analysis- (m2/s2)*(kg/m3)

@MiniUniverse_RA

2 жыл бұрын

@@nickjohnsonn9761 I think so, but I highly recommend that validate the results with a experimental results. It's a long time since I have worked on this problem.

@avion3698

2 жыл бұрын

@@MiniUniverse_RA but what you're showing simply gives pressure in certain normal direction which is N/m2 so I think we have to multiply by the cell surface areas too

@MiniUniverse_RA

2 жыл бұрын

@@avion3698 No, it's not. It is force.