Uploaded April 2018 | Updated September 2026, 1 week ago

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Let's run a CFD simulation of a normal shock in a converging-diverging (CD) nozzle! In this video, we will go through step-by-step how to set up the problem, run it, and analyze the solutions. Note that it would help to have watched the videos I list down in the Relevant Videos section.

===== NOTES =====
► I'm using the MARKER_FAR boundary condition to set the throat, or inlet, values. You can also use the MARKER_SUPERSONIC_INLET boundary condition and get the same results.
► I'm not quite sure why the throat values are slightly off even though the solutions converged. Part of me thinks it has to do with the Mach number being set to 1 (or close to 1, since I've tried it with it slightly above 1 as well with the same results). The way that problems are solved when they are subsonic vs. supersonic changes, and since it's straddling that line, it might be difficult. Without looking at the numerics and spending too much time on this, it's hard for me to say. If you figure it out or have any comments/suggestions, let me know.

===== RELEVANT LINKS =====
► CFG and SU2 files used in this video
joshtheengineer.com/2018/04/16/cfd-with-su2-normal-shock-in-cd-nozzle

► NSN MATLAB code
joshtheengineer.com/2018/01/24/normal-shock-in-converging-diverging-nozzle

===== RELEVANT VIDEOS =====
→ Converging-Diverging Nozzle Explained
bit.ly/CDNozzleExplained

→ Pressure Ratio Delineations
bit.ly/PressureDelineations

→ Calculating Normal Shock in Nozzle
bit.ly/CalculatingNSN

→ Isentropic Supersonic CFD Simulation
bit.ly/IsentropicSupersonic

→ GMSH: Rocket Nozzle Mesh
bit.ly/GMSHRocketNozzle

→ How To: Install SU2
bit.ly/InstallSU2

→ CFD Example in SU2
bit.ly/SU2Example

===== FREE SOFTWARE =====
► SU2 Download
su2code.github.io/download.html

► GMSH Download
gmsh.info

► Paraview Download
paraview.org/download