VSPAERO 's Panel Method

[Eric Cheng]

Hello everyone,

When I calculate the aerodynamic characteristics of a wing with  propellers, I want to know whether the Panel Method in VSPAERO is a time accurate method(unsteady method) or a steady method?

This is really important to me, because I deeply know that the RANS method of CFD software is a time accurate method. I really want to confirm that the Panel Method in VSPAERO belongs to a low-order steady method that can be quickly calculated?

Eric

[Brandon Litherland]

Eric,

The Panel mode is a thick surface potential method similar to VLM mode.  By default it is steady but be aware that vspaero can be run in unsteady mode from the command line.

[Eric Cheng]

Brandon,

Okay, so that's it, thank you very much for your reply.

So is it based on Panel Method when running in unsteady mode from the command line?

[Brandon Litherland]

You can run Panel or VLM.  There are additional input files needed to perform a command line unsteady run.  Once I'm off of the Workshop organization and presentations I'll be working on Chapter 3 of the VSP Ground School which will cover VSPAERO as well as other analyses.  How to do this will be included.

[Eric Cheng]

Brandon, 

Thank you very much for your suggestions.，and I will attend this year's OpenVSP seminar(workshop) on time in October.

After your reply, I now know that Panel Method is also a low-order steady method.

In addition, what I also want to know is when simulating a wing with a propeller, is the method of modeling the propeller as Blades a time accurate method(unsteady)?

Eric

[Brandon Litherland]

In the GUI, rotating blades will activate the unsteady vspaero mode.  This is specific to blades but groups of components can be flagged as Fixed, Dynamic, or Rotor in the *.groups file.  This gets into more advanced operation but you will configure the geometry within VSP and then run VSPAERO from the command line.  

[Rob McDonald]

Panel (and VLM) methods can be steady or unsteady.

VSPAERO can be run in both steady or unsteady modes.  Most of the time, it is run in steady mode -- with wakes that are adapted in a way that is not guaranteed to be time accurate.

The OpenVSP GUI only tells VSPAERO to run in unsteady mode when needed.  From the GUI, this only happens for Unsteady P, Q, R Stability analysis and when running with rotating blades like a prop or a rotor.

The actuator disk calculation is steady -- but if you model the propeller with rotating blades, it is an unsteady calculation by default.

There are some other clever ways to run a propeller case that may be steady or pseudo-steady, but this is good enough for now.

Rob

[Eric Cheng]

Brandon & Rob,

Thank you for your reply, I am much clearer about this.thanks again!

Eric