5.1 Boundary Conditions
Setting appropriate boundary conditions is vital for a successful simulation. Ill-posed boundary conditions will lead to physically incorrect predictions, and in many cases solver failure. Users must specify the boundary conditions for each solved field. The tutorials provided with OpenFOAM show examples of good practice in terms of selection and application for various cases.
Boundary conditions are organised into categories for easier navigation, comprising:
- basic
- basic types
- fixedValue
- fixedGradient
- mixed
- …
- constraint
- geometrical constraints
- symmetry
- wedge
- empty
- cyclic
- …
- derived
- specialised conditions
- fixedProfile: to specify a profile of a variable
- swirlFlowRateInletVelocity: to specify velocity inlet for a swirling flow providing flow rate
- inletOutlet: outlet condition with handling of reverse flow
- codedFixedValue: fixed value set by user coding
- …
In all there are more than 70 boundary conditions. The list of all available boundary conditions divided into categories based of the use can be found in section A.4
An example pressure field file is shown below
17dimensions [1 -1 -2 0 0 0 0];
18
19internalField uniform 1;
20
21boundaryField
22{
23 inlet
24 {
25 type fixedValue;
26 value uniform 1;
27 }
28
29 outlet
30 {
31 type waveTransmissive;
32 field p;
33 psi thermo:psi;
34 gamma 1.4;
35 fieldInf 1;
36 lInf 3;
37 value uniform 1;
38 }
39
40 bottom
41 {
42 type symmetryPlane;
43 }
44
45 top
46 {
47 type symmetryPlane;
48 }
49
50 obstacle
51 {
52 type zeroGradient;
53 }
54
55 defaultFaces
56 {
57 type empty;
58 }
59}
60
61// ************************************************************************* //
18
19internalField uniform 1;
20
21boundaryField
22{
23 inlet
24 {
25 type fixedValue;
26 value uniform 1;
27 }
28
29 outlet
30 {
31 type waveTransmissive;
32 field p;
33 psi thermo:psi;
34 gamma 1.4;
35 fieldInf 1;
36 lInf 3;
37 value uniform 1;
38 }
39
40 bottom
41 {
42 type symmetryPlane;
43 }
44
45 top
46 {
47 type symmetryPlane;
48 }
49
50 obstacle
51 {
52 type zeroGradient;
53 }
54
55 defaultFaces
56 {
57 type empty;
58 }
59}
60
61// ************************************************************************* //