I’ve very new to CFD (I’m an Electrical Engineer), so maybe some questions I ask are a bit premature

and I’d discover them myself working through the tutorials, so I’m a bit wary of asking,

but my enthusiasm is now, so I’ll ask anyway. I have commenced SimScale Academy

and bought Batchelor’s Introduction to Fluid Dynamics, so hopefully will catch up soon.

Ultimately I’m Looking to simulate a rotating solar collector as summarized here… https://tinyurl.com/rotatingsolar1 with more detail in the original thesis… https://www.builditsolar.com/Experimental/RSB/The_RSB.pdf

I’m thinking the Conjugate Heat Transfer might be a good fit (after I finish the webinar on that)

to cover heat dissipation to the environment, but in the meantime I’m trying a simpler system

without heat transfer. The original project only ran at modest rpm, but I want to understand the pressure stratification at high rpm - and later with low pressures of the order of 1 Pa.

So here is my simpler project for simulating air in a rotating cylinder as a Laminar Steady-State Compressible Gas with a MRF Rotating Zone applying the rotation.

Run2 @ 100rad/s does produce some pressure stratification as expected

But I wonder if the pressure may be different in the center, so I add a cutting plane and get…

which doesn’t show the pressure profile in the middle plane. So…

```
Q1. How can I show the pressure gradient in the middle plane?
```

Now even though the solution ends up physically plausible, the residuals are poor…

Now I have to admit, I don’t know what all these specific residuals are. “Ux/y/z” is straight forward, but I’m only presuming “p” is pressure and “h” I have no idea, and my google-fu is failing me. So…

```
Q2. Where can I read about the meanings of the residuals?
```

Just changing the speed with Run 3 at 1000rad/s seems to produce a better result with more stratification…

and better looking residuals…

but I don’t know the significance of the “p” rising after the minima near 100s. How might it be interpreted? (Q3)

And maxing out the speed with Run 4 at 10000rad/s seems broken - the stratification is lost and the negative pressure seems implausible…

and the velocity residuals oscillate badly…

so its easy to guess I’ve exceeded the bounds of the solver, but I’d really like to get a sim to work at this speed.

There exist real-life turbines that spin at this speed, and this plays into other ideas I want to investigate.

So rather than thrash around burning compute time I thought I’d just ask…

```
Q3. I imagine that at that high speed, a finer time resolution might be appropriate before making the mesh smaller?
Q4. Is a laminar flow suitable for this?
Q5. Are No-slip walls correct? I've since read that No-slip is for viscous fluids which stick to the wall, which doesn't sound like gas.
Q6. I'd like to re-do exactly Run3 by change it from No-slip to Slip, but I've lost track of several setting changed a few days ago? Now because I'm lazy, how to I copy the archived-Run3-settings to the current-settings so I only need to make that single change before the the next run?
```

Cheers, Ben