[Jackzm]

Hello, everybody.
I‘m working on a stirred vessel with gas and water. I would like to know the torque value of my stirred vessel.
As we know, the CFD-post can give us the torque value by air and water separately. But I find that, in one of my simulations, the torque of air is negative and the water of torque is positive. And the total torque is the sum of air and water’s torque.

But surprising me, in some of my other simulations, the torque values of air and water are both positive.

Could you tell me why did these happen？

PS:
1. My model is a stirred vessel with diameter 700mm, Height 530mm, total volume 0.2 m3, and mesh grid 530,000.
2. The Euler-Euler model, MRF model, k-εmodel .etc were chosen.
3. The drag coefficient is 0.44.