The forces
function object generates aerodynamic force and moment data for surfaces and porous regions, with optional
Forces comprise normal pressure
\[ \vec{F}_p = \sum_i \rho_i \vec{s}_{f,i} \left(p_i - p_{ref}\right) \]
and tangential viscous contributions:
\[ \vec{F}_v = \sum_i s_{f,i} \dprod \left(\mu \tensor{R_{\mathrm{dev}}} \right) \]
Where \( \rho \) is the density, \( \vec{s}_{f,i} \) the face area vector, \( p \) the pressure \( \mu \) the dynamic viscosity and \( \tensor{R_{\mathrm{dev}}} \) the deviatoric stress tensor.
Basic operation of the forces
function object comprises:
forces1 { type forces; libs ("libforces.so"); patches (<list of patch names>); }
For more complete control, the full set of input entries includes:
forces1 { // Mandatory entries type forces; libs ("libforces.so"); patches (<list of patch names>); // Optional entries // Field names p p; U U; rho rho; // Reference pressure [Pa] pRef 0; // Include porosity effects? porosity no; // Store and write volume field representations of forces and moments writeFields yes; // Centre of rotation for moment calculations CofR (0 0 0); // Spatial data binning // - extents given by the bounds of the input geometry binData { nBin 20; direction (1 0 0); cumulative yes; } }
Default behaviour assumes that the case is compressible. For incompressible cases, i.e. solved using the kinematic pressure the rho
entry can be used to set the free stream density:
rho rhoInf; rhoInf 100000;
Text reporting:
Sum of forces Total : xxx Pressure : xxx Viscous : xxx Porous : xxx Sum of moments Total : xxx Pressure : xxx Viscous : xxx Porous : xxx
Optional storing and writing of force and moment fields:
forces
moments
Storing of integrated values for further post-processing:
normalForce
tangentialForce
porousForce
normalMoment
tangentialMoment
porousMoment
Related:
Source code:
Example usage:
propeller
tutorial: $FOAM_TUTORIALS/incompressible/pimpleFoam/RAS/propellerWould you like to suggest an improvement to this page? | Create an issue |
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