Practical Course SC & VFree Boundary Value Problems

Prof. Dr. Hans-Joachim Bungartz

Institut fürInformatik

Scientific Computingin Computer Science

Discrete Boundary Conditions

• five types of surface cells

discrete stress = 0

auxiliary construct: gravity

compute values only once!

• definition of boundary conditions:

variables to be fixed

available relations / laws

Surface Cell Types

1 empty neighbour

Surface Cell Types

2 empty neighbours, across

Surface Cell Types

2 empty neighbours, opposite

Surface Cell Types

3 empty neighbours

Surface Cell Types

4 empty neighbours

Algorithm (Time Step)

(1) compute time step dt (particle positions)

(2) mark fluid/surface/empty cells

(3) set boundary values (+ free surface)

(4) compute preliminary velocities

(5) solve pressure equation

(6) compute final velocities