Boundary Condition Implementation

• Implicit BCs are used in PUMA when any of the implicit time-integration schemes are used (i.e. the BC is evaluated at the next timestep as opposed to the current timestep).
• The boundary condition Jacobian J_BC ($\frac{\partial Q_{BC}} {\partial Q}$) is obtained numerically using central differences, which is completely general and does much to improve the maintainability of the code.
• There are several types of BCs implemented in PUMA, and more can be added without much difficulty as and when wanted.

1 Fixed at freestream

$$\rho$$ 2 Fixed at given values

3 First order extrapolation from the interior

4 Second order extrapolation from the interior

5 Inflow/outflow (Riemann)

6 Specified p₀, T₀ p₀, T₀

7 Fixed back pressure pressure p

8 Tangency

9 No slip adiabatic wall

10 No slip fixed­temperature wall T_wall T_wall

11 Zero u velocity

12 Zero v velocity

13 Zero w velocity