Aerospace Engineering Iowa State University 311L Fall 2003 CFD Exercises 1 Course : Aer E 311L Gas Dynamics Lab

Aerospace Engineering Iowa State University 311L Fall 2003 FLOWLAB - USAGE Flowlab is installed in the windows labs. Go to “Start” -> “All Programs”. Run “Flowlab1.1”. This creates a file called “Flowlab.ini” in C:\Documents and Settings\”user”. It looks as follows – FLOWLAB_WORK_DIR C:\Temp\myflowlab FLOWLAB_TEMPLATE_DIR z:\Flowlab1.1\templates\nozzle All your work is saved in FLOWLAB_WORK_DIR. Remember to copy your final files to your home area in Clue or AFS. Add AFS directory in the following way. Start the AFS client. Add \afs\iastate.edu\general\aero311l\Flowlab1.1\templates as F:\ Define FLOWLAB_TEMPLATE_DIR to F:\

Aerospace Engineering Iowa State University 311L Fall 2003 Create a nozzle without plenum with the following dimensions L1 =.1016 L2 =.0368 R1 =.0128 R2 =.0101 R3 =.0114 FLOWLAB - GEOMETRY

Aerospace Engineering Iowa State University 311L Fall 2003 FLOWLAB - PHYSICS For the nozzle without plenum generated in previous exercise, set the boundary conditions in Flowlab by the following specifications. Choose inviscid model. Inlet Total pressure Pa Total temperature K Outlet and plenum Pressure (static) – Pa Temperature (static) – 300 K

Aerospace Engineering Iowa State University 311L Fall 2003 FLOWLAB - MESH Continuing from the previous problem, create mesh using “automatic->medium” option. The mesh should look like the following.

Aerospace Engineering Iowa State University 311L Fall 2003 FLOWLAB – SOLVE/REPORTS Using the results for previous problems, and the default settings for converge criteria ( note the value ), “solve”. Generate mach number plot at centerline.

Aerospace Engineering Iowa State University 311L Fall 2003 FLOWLAB –POST PROCESSING Generate contour plots for density, pressure and mach number for the nozzle. Contour plot for mach number.

Aerospace Engineering Iowa State University 311L Fall 2003 FLOWLAB –SUGGESTIONS The display for the residual (XY plot) does not refresh properly if a new run is submitted after a previous run in the same section. Workaround – Start a new session. Try to save your work as often as possible. Most of the defaults are set to the nozzle dimension in the experiment. Use them. If the pressure ratio is low, and the computational domain is large, there are convergence problems. So when having convergence problems, go for a small domain.