MUSST is a set of modern fortran subroutines dedicated to the resolution of some lubrication problems.
MUSST implements the finite element method on Reynolds' equation. It can solve a large variety of problems with standard geometries like sliders, bearings and pockets.
However, the user can provide the surface heights (as a .sur file for instance), whatever the surface.
The lubricant that can be modelled are perfect gases, incompressible fluids and compressible fluids (treated as gaz-fluid mixtures [1]). The latter allows for cavitation phenomena to appear.
The objective of the multiscale approach is to study flows between large rough surfaces needing very fine meshes while maintaining a reasonable computation time. For this purpose, the domain is split into a number of subdomains (bottom-scale meshes) connected by a coarse mesh (top-scale). The pressure distribution at the top-scale is used as boundary conditions for the bottom-scale problems. This pressure is adjusted to ensure global mass flow balance between the contiguous subdomains.
This multiscale method allows for a significant reduction of the number of operations as well as a satisfactory accuracy of the results if the top-scale mesh is properly fitted to the roughness lateral scale. Furthermore the present method is well-suited to parallel computation, leading to much more significant computation time reduction [2].
MUSST needs to call efficient sparse linear system solvers like MUMPS, UMFPACK,
SuperLU or MA48. As the use of the latter is restricted, the MSOLV makefile has to be tuned accordingly.
If the user can supply the following files :
MSOLV/src/hsl_common90.f90MSOLV/src/hsl_ddeps90.f90MSOLV/src/hsl_ma48d.f90
and
MSOLV/lib/libhsl_ma48.a
then MA48_LIB = 1, otherwise MA48_LIB = 0.
To build the whole package: $cd MUSST and $make all. To build MUSST core, $make, or $make debug, $make gprof, $make clean.
To launch some test examples:
$./main cfg/TEST_01.dat-> slider bearing, deterministic, incompressible$./main cfg/TEST_02.dat-> journal bearing, deterministic, compressible$./main cfg/TEST_04.dat-> rough surface, deterministic, compressible$./main cfg/TEST_05.dat-> pockect bearing, deterministic, perfect gas$./main cfg/TEST_11.dat-> slider bearing, multiscale, compressible$./main cfg/TEST_14.dat-> rough surface, multiscale, compressible
[1] Brunetière N. A General Model for Liquid and Gas Lubrication, Including Cavitation. ASME. J. Tribol. 2017;140(2):021702-021702-10. DOI
[2] Brunetière, N.; Francisco, A. Multiscale Modeling Applied to the Hydrodynamic Lubrication of Rough Surfaces for Computation Time Reduction. Lubricants 2018, 6, 83. DOI