Fluids

Topics relate to Fluent, CFX, Turbogrid and more

Compressed Air to Flush out water on tank

• Shayne Ondray
Subscriber

I am designing a tank that will use compressed air to flush out water inside the tank.

• Nikhil Narale
Ansys Employee

Hello,

• Shayne Ondray
Subscriber

What does this mean?

• Nikhil Narale
Ansys Employee

It appears that the solution is diverging. Firstly, check the mesh quality, particularly the minimum orthogonal quality. Secondly, you can try reducing the time step size. A smaller time step allows for better accuracy in capturing the physics of the problem and can help stabilize the solution. It's recommended to keep the CFL number as close to 1 as possible, as this ensures stability and accuracy.

• Shayne Ondray
Subscriber

I wanted to check how much pressure of compressed air I need to put in the tank to flush out water.

I am in doubt of the ff:

1. do I need to model my tank in 3D instead of 2D?
2. Am I correct that my analysis shall be in euclidian 2 phase? See enclosed photo

• Nikhil Narale
Ansys Employee

1: If the problem involves complex geometry or flow patterns that cannot be accurately captured in 2D, then a 3D model would be necessary to obtain accurate results. However, if the problem is relatively simple and the flow is primarily in one direction, then a 2D model may be sufficient.

In general, 3D models can provide more detailed and accurate results but are computationally more expensive compared to 2D models. Therefore, the choice between 2D and 3D modeling should be based on the specific requirements of the problem and the available computational resources.

2: That's correct. One phase would be water, and the other would be air. You may have to patch (initialize) the water in the domain. VOF model will track the distinct interface between the two phases.

• Shayne Ondray
Subscriber

thank you for the explaination Nikhil. My problem's requirement is to identify how much pressure I need to put into the tank to flush out the water. would you think 3D model will be benificial on this scenario?
thanks again

• Nikhil Narale
Ansys Employee

Based on the specifics of the situation, I recommend utilizing a 3D approach. This is due to the fact that the diameter or width of the inlet/outlet pipe or duct varies from that of the container, which necessitates accounting for 3D effects.

• Shayne Ondray
Subscriber
Thank you
• Nikhil Narale
Ansys Employee

You're welcome!