{"id":50930,"date":"2020-12-30T01:58:55","date_gmt":"2020-12-30T01:58:55","guid":{"rendered":"\/forum\/forums\/topic\/simulation-of-a-jet-of-air-into-a-shock-tube\/"},"modified":"2020-12-30T01:58:55","modified_gmt":"2020-12-30T01:58:55","slug":"simulation-of-a-jet-of-air-into-a-shock-tube","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/simulation-of-a-jet-of-air-into-a-shock-tube\/","title":{"rendered":"Simulation of a jet of air into a shock tube"},"content":{"rendered":"
\n
\n

I am simulating the resulting turbulent flow generated from injecting air at a supply (absolute) pressure of 202.65 kPa through an inlet of diameter 0.5", into a shock tube that has an initial (absolute) pressure of 101.325 kPa. The dimensions of the rectangular shock tube's cross section are 2.5"x1.5". I am only modelling a portion of the length of the shock tube, shown below. When I hit Calculate, the residuals start off below 1, and then the x, y, z equations shoot up to the order of 10's and 100's. I hope somebody can help me troubleshoot what is supposed to be a simple turbulence simulation.<\/p>\n

My flow is compressible so I selected the density-based solver. Transient flow is selected as well. I am using the k-omega model to model the turbulence, and my solution method is implicit. I set 3 boundary conditions:<\/p>\n

1) inlet: pressure-inlet –> Gauge pressure total pressure is set to 101325 Pa, and supersonic\/initial gauge pressure is set to 0 (i also tried different pressures here)<\/p>\n

2) left and right planes indicated in the diagram: both set as pressure-outlet –> gauge pressure is set to 0 as that is the gauge pressure in my shock tube at those two locations<\/p>\n

Are the boundary conditions correctly set? Is anything missing?<\/p>\n

In the solution initialization, I am computing from inlet, where the Y-velocity is automatically set to -329 m\/s2. <\/p>\n

The below attached images are of the shock tube, the fluid domain (air) that I am modelling, the mesh, and the set boundary conditions in FLUENT.<\/p>\n

\n
\n
\n\"Capture1.JPG\"
\n<\/a><\/p>\n","protected":false},"template":"","class_list":["post-50930","topic","type-topic","status-closed","hentry","topic-tag-ansys-mechanical","topic-tag-ansys-student","topic-tag-fluid-dynamics","topic-tag-fluid-flow","topic-tag-transient"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t