Hi, I'm quite new to CFD and I'm having major problems with meshing. I'm studying the drag coefficient on an elliptical and tangent ogive nose cone and I'm using a 2D axisymmetric geometry. From what I read on literature it's important to have y+ close to 1 on the first layer near the wall, because with this setup the model (k-omega SST in this case) doesn't need to use wall functions. I don't understand from what criteria I need to subdivide the edges or what element size to use to have an accettable mesh; then in ansys meshing if I use a general mesh element size to small (and I don't know what is too small for it) the meshing process get's stuck at 5% when converting triangular elements to quads. Is there any literature, videos or piece of knowledge I should read or watch to really understand meshing? I feel like I'm walking in the dark. If needed I will upload the domain I was trying to mesh.

I’ve just got my first potential customer, and I’m willing to compromise on the money for some brand visibility. I wonder generally what’s the pay?

They have a small electronics box and want to run the analysis on it.

I’m an employed fresher engineer with a BSc in Mech engineering if this is relevant

Hello everyone.

I’m trying to replicate some experimental analysis with Ansys Fluent. Particularly I’m trying to simulate a Wells turbine on different airflow conditions (same RPM, different inlet velocities).
The goal is to plot torque and pressure coefficients over time/flow coefficient.
I’m getting very bad torque values, about 50% of the experimental results (more on that below).

Here’s the setup:

I created a CAD with same exact geometry features of the tested turbine.

I imported it into Ansys, considered just the duct in which the air flows (just like the OWC simulator in the real test). Divided the domain into 3 zones, two stationary and 1 MRF. (I considered no tip gap to avoid strange behavior there, since 1mm of gap it could be hard to simulate). Also, only simulated 1/6 of the turbine, a single blade passage (6 blades in tot)

Meshed and open fluent.

The solver is Ansys Fluent, I set up the air conditions (viscosity and density). I set up the MRF rotational speed and inlet velocity on 9m/s (i want to get one condition right before analyzing more intel speed values). Used k omega.

I initialized and run 500/1000 iterations.

Data obtained:

CFD (Torque on a single blade):

Pressure: 0.016280575 Nm
Viscous: 0.0025203426 Nm
Total: 0.018800917 Nm

Experimental results at 65Hz and 9m/s of inlet speed vel:

0.206 Nm, which divided by 6 give me: 0.0343 Nm

That's about 54% of the exp data

Thanks everyone:)