[Elaheh 1995]

hello, i hope you are doing great. i have got some questions about flow 3D and i need your help

1) i want to model a channel that has a tank of water and there is a pump that sends water to the channel constatly. i don't know how to define the pump function.
2) also i want a finer mesh near channel and coarser mesh for tank and i need the mesh to gradually increas but i have no idea how to do that either.
i would really appreciate if you could help me with my questions.
favorized with 10 cm edge.PNG
thanks in advance

[redlemon44]

This shows the pump function:
https://www.youtube.com/watch?v=ptF1U4PXaFs

FLOW-3D’s new axial pump model allows users to mimic the net effect of an axial pump in their simulations. There are two options with respect to the pump behavior. The first option is to prescribe either a volumetric flow rate or a flow velocity through the pump so that the fluid is moved at the specified rate. This option is appropriate when an operating flow rate is provided for the pump. The second option provides a more complete definition of the pump operation based on a pump performance curve

[MSM1985]

For discharge feeding, you can either use a pump function or discharge boundary condition at the inlet of channel, whichever is more closer to the real problem.

For meshing, you can use a nested mesh block. 1st mesh can be coarser and covers whole domain. 2nd mesh block should be confined to channel and must be finer. The ratio of cell size size between 2 mesh blocks should be 1:2.

I am not aware if we can provide gradually increasing meshes in flow 3D. If that's the case, it will be tricky and computational intensive.

[Elaheh 1995]

thanks for your response, it makes sense. I will try it

[Elaheh 1995]

Originally Posted by MSM1985

For discharge feeding, you can either use a pump function or discharge boundary condition at the inlet of channel, whichever is more closer to the real problem.

For meshing, you can use a nested mesh block. 1st mesh can be coarser and covers whole domain. 2nd mesh block should be confined to channel and must be finer. The ratio of cell size size between 2 mesh blocks should be 1:2.

I am not aware if we can provide gradually increasing meshes in flow 3D. If that's the case, it will be tricky and computational intensive.

thanks MSM1985, the meshing explanation was clear to me, but I will need more help with the pump function. should I design a pool so that water could be pumped from it? or should I create a specific component like a cylinder that can be a pump? or I should copy my whole geometry and define it as a pump in the (Fan/Impeller and Pump section). and about the boundary condition do you mean pressure by "discharge boundary condition" or else?

[MSM1985]

As you showed in the figure, water is entering from bottom of the tank into the channel. In this case, volumetric flow rate at Xmin boundary shall do the job.
But if you want to see axial and swirl flow effects induced by pump, then you have to define a separate component, preferably cylinder (option available geometry widget). Define this component as 'Pump' with pump properties. Such components are called 'phantom' which regulates flow but does not block flow.

[Elaheh 1995]

Originally Posted by MSM1985

As you showed in the figure, water is entering from bottom of the tank into the channel. In this case, volumetric flow rate at Xmin boundary shall do the job.
But if you want to see axial and swirl flow effects induced by pump, then you have to define a separate component, preferably cylinder (option available geometry widget). Define this component as 'Pump' with pump properties. Such components are called 'phantom' which regulates flow but does not block flow.

thanks a lot. it was a really good explanation. I don't need axial and swirl flow so I will modify my boundary condition settings. thanks again you really helped me.