[wind]

Hi, everyone,

I am simulating the hydraulics of tangential vortex intake for drainage. Please see the picture for model demonstration.

Some cases are calculated. The problem is :
the initial results show that the air core in the vertical circular drainpipe is larger than that in experiment. (It means that the water in the drainpipe drops down faster than expected, and less water accumulates in the junction part of intake)

The inflow discharge keeps the same with experiment, and the free surface elevation on horizontal approach flow channel is checked to be almost same with the test curve.

I hesitate that the numerical errors might be related to:

1. Turbulence model: whether RNG model is sufficient to simulation this highly vortex flow in pipe ? The average inflow velocity is not very high, just about 0.6 m/s.

2. Advection term: whether First order is accurate enough?

3. Mesh size: Even for the coarse mesh size of 0.01 m (0.8 million cells) , the computation time will be nearly 1.5 days. Should the mesh size be much refined?

Could you kindly give me some advice or any comments?

Thank you very much and happy new year!