Learning Forum

[Hyejin Chae]

Hi I'm a total novice at cfd.
I'd really appreciate your help.

There is a big tank about 100m3, and there is no impeller in the tank.
Here's the same concentration of the material in the tank, but there's a purified inlet, and there's an inlet that just circulates in. Outlet is one. It goes out of the outlet and then is divided into two, one is refined and the other is simply circulated. The area of the inlet and outlet is very small, about 0.008m2

I want to know the blending time due to the refined inlet.

What model should I use? First, I tried using the Species transport and k-omega model.

1. But I saw the velocity vector and found out that it was around the inlet at 4000m/s. I don't understand this happening. Even if there is an inlet or outlet in a very large tank, is it right to have such a large fluidity when it is a very small area? Usually it moves up to 5m/s in a liquid pipe, but I don't understand this phenomenon.

2. I would really appreciate it if you could help me with which model I should use to interpret this model and how I should approach it.

[Rob]

Check the fluid you have attached to the cell zone, and the domain scale. You won't be the first person to have picked the wrong fluid or accidentally scale from m to mm / mm to m in a model. 

You've picked up that the result is rubbish - that's a good start. Have a look in Learning and Help as I'm sure there's a mixing tank example/tutorial somewhere on the system.