Week 7: Shock tube simulation project
Aim: Shock tube simulation project
Objective:
- Setup a transient shock tube simulation
- Plot the pressure and temperature history in the entire domain - Explain the result
- Plot the cell count as a function of time - Explain the result
It is expected to show the mesh generation using ParaView.
Also, create animation and upload it on Youtube and provide the Youtube link for animation in your report.
Introduction
The shock wave is an instrument used to direct and replicate shock waves in order to simulate the actual explosion and its effects usually on a smaller scale. It is also used to study aerodynamic flow under a wide range of temperatures and pressures that are difficult to obtain in other types of testing facilities. They are also used to investigate compressible flow phenomena and gas-phase combustion reactions. More importantly, they are used in
he plot shows the different types of waves that are produced after the diaphragm is ruptured.
Shock waves are produced by using a high-pressure build-up that causes the diaphragm to burst resulting in shock waves traveling down the tube.
Application
It is used to measure the rates of chemical kinetics. It is also used in aerodynamic tests. It is also used to measure the dissociation energies and molecular relaxation rate.
Case-setup
Case-setup
The shock_tube. STL file is loaded into the Converge-CFD set-up.
The diagnosis dock is selected from the "View" option and the "Find" option is selected. It is found that there are ("Intersections(0)","Nonmanifold Problems(12)","Open Edges(0)", "Overlapping Tris(0)","Normal Orientation(0)","Isolated tris (0)".
Therefore the diaphragm connecting the two regions is deleted to remove the non-manifold error.
The "Normal Toggle" is selected from the ribbon, upon selecting the normal toggle it was observed that the normal is pointing outside the volume, technically the normal should point inside the volume where the fluid is flowing. Therefore in the geometry dock, the "Transform" option is clicked. The "Normal" tab is selected from the geometry dock and one of the triangles containing the normal pointing outward is selected. The "Apply" option is selected for removing the normals.
The "Case Setup Dock" is selected from the "View" and "Begin Case Setup" is executed.
The "Time" based "Application" type is selected. The "Material" is selected and the predefined mixture is selected as air. The "Reactant mechanism" is checked off because it is not a combustion problem. The species is selected and the "Apply" is clicked. Under "Gas simulation" the Equation of state is selected as "Redlich Kwong", the critical temperature is 133K and the critical pressure is 3770000Pa. The Turbulent Prandtl number is 0.9 and the Turbulent Schmidt number is 0.78 under Global Transport parameters. The [Math Processing Error]O2 and the [Math Processing Error]N2 are selected as species. Under "Run parameters" the "Transient-state solver" is selected. The "Temporal type" is Time-based simulation. The "simulation mode" is selected as "Full Hydrodynamic" because the geometry is simple so while creating the mesh inside the geometry it solves the NS equation as well, but if the geometry is complex "No hydrodynamic solver" is selected as such if there is an error it will point out immediately while creating the mesh, otherwise if the hydrodynamic solver is selected then it will be very tedious to identify the error in the simulation case set up.
Under "Simulation time parameters" end time is chosen as 0.003s (steady-state). The initial and minimum time step is 1e-09 s. The maximum time step is 1s, and the maximum convection CFL limit is 1 and the rest are default values.
The "Pressure" "Equation" is selected under the "Solver parameter" and the "Preconditioner" is selected to "None". The "Maximum convection CFL limit (final stage)" is set to 0.5. The "Density-based solver" is selected it is suitable for even low Mach numbers to avoid extrapolating temperature calculations and the PISO coupling scheme is selected.