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Outputs
MachLine can be configured to produce several different outputs once the flow solution has been computed. These outputs are specified in the Output section of the input file. There are essentially four types of output from MachLine: body results, control point results, wake results, and slice results. Each are discussed in the following sections.
MachLine will output singularity strengths, velocities, pressures, etc. on the surface of the body being analyzed. If the mesh is being mirrored and the freestream flow is not symmetric with the mesh, then the calculated results on the mirrored half of the mesh may also be exported.
The reported surface velocities are always evaluated at the centroid of each panel. The surface pressures are the average across each panel.
To solve the Dirichlet formulations, MachLine places a number of control points inside the configuration and enforces certain conditions at these control points. If specified, MachLine will output the type of condition enforced at each control point and the residual in the linear system at that control point. The conditions which may be enforced at the control points are:
| BC_type | Description |
|---|---|
| 1 | Zero perturbation potential. |
| 2 | Inner potential for source-free formulation. |
| 3 | Zero perturbation mass flux (linearized). |
| 4 | Doublet strength matching. |
For lifting flows, MachLine will generate a wake mesh emanating from sharp trailing edges. This mesh is separate from the body mesh and so is exported separately. MachLine will export the shape of the wake and the doublet strength on the wake. Due to the nature of the wake, only one wake is ever generated, regardless of mesh mirroring and flow symmetry.
To view off-body results, the user has the option to have MachLine calculate the velocity potentials (freestream, total, source-induced, doublet-induced, induced) at an arbitrary number of points. These points are supplied to MachLine via a csv file. The data at these points will be written out to a csv file and may then be rendered using data analysis software.
The solver status codes are as follow:
| Code | Meaning |
|---|---|
| 0 | Run was successful. |
| 1 | An invalid value was detected in either the A matrix of b vector after assembling the linear system of equations. |
| 2 | Either a control point was uninfluenced or a panel exerted no influence. |
| 4 | The linear system solver failed (non-convergence, singular matrix, etc.). |