Compute 'Cp' from 'dCp'

[Reji Rejish]

Hi OpenVSP Team, 

1. When I use GUI, VLM method gives me 'dCp' at a selected spanwise location, PANEL method gives me 'Cp' at the selected spanwise station. 

Is there any way to convert 'dCp' to Cp at the selected spanwise location?

2. When I use C++-API to extract results using 'CpSlice_Wrapper' I am getting 'dCp' for both VLM and PANEL methods. Only data name changes not the values in the results.

For example, I need to use 'dCp' for VLM and 'Cp' for PANEL, however both gives me the pressure difference (dCp) along the chordwise direction. 

 

Please let me know if I need to use different ways to extract 'Cp' for VLM method.

At the moment I am using the version 3.26.1, soon I will move to the latest.

Best regards, 

Rejish

[Rob McDonald]

On Tue, Apr 26, 2022 at 7:07 AM Reji Rejish <rejis...@gmail.com> wrote:

Hi OpenVSP Team, 

1. When I use GUI, VLM method gives me 'dCp' at a selected spanwise location, PANEL method gives me 'Cp' at the selected spanwise station. 

Is there any way to convert 'dCp' to Cp at the selected spanwise location?

No.  A thin-surface mode can only figure out pressure differential, not pressure. 

 

2. When I use C++-API to extract results using 'CpSlice_Wrapper' I am getting 'dCp' for both VLM and PANEL methods. Only data name changes not the values in the results.

For example, I need to use 'dCp' for VLM and 'Cp' for PANEL, however both gives me the pressure difference (dCp) along the chordwise direction. 

 

The variable name may be the same, but the quantity should be dCp or Cp as appropriate.  The values should certainly change -- perhaps you are accessing the same Results ID -- each analysis run will create a new unique Results ID.

 

Please let me know if I need to use different ways to extract 'Cp' for VLM method.

At the moment I am using the version 3.26.1, soon I will move to the latest.

It is good to update -- but I don't think any of this will change for you going to 3.27

Rob

 

[Reji Rejish]

Hi Rob, 

Thank you very much for your reply. 

I will check the Results ID to get the appropriate dCp and Cp values.

Best regards, 

Rejish