Initially this case will be run with a Reynolds number of 10, where the Reynolds number is defined as: The keyword for kinematic viscosity is nu, the phonetic label for the Greek symbol by which it is represented in equations. The user can check that the kinematic viscosity is set correctly by opening the transportProperties dictionary to view/edit its entries. For an icoFoam case, the only property that must be specified is the kinematic viscosity which is stored from the transportProperties dictionary. The physical properties for the case are stored in dictionary files in the constant directory.
The top surface moves at a speed of 1 m/s in the -direction so requires a fixedValue condition with value of uniform (1 0 0). The other patches are walls: a no-slip condition is assumed on the fixedWalls, hence a noSlip condition. The boundary field for velocity requires the same boundary condition for the frontAndBack patch. uniform (0 0 0) (see section 4.2.5 for more information). The dimensions are those expected for velocity, the internal field is initialised as uniform zero, which in the case of velocity must be expressed by 3 vector components, i.e. The user can similarly examine the velocity field in the 0/U file. Here the pressure is kinematic, and as an incompressible case, its absolute value is not relevant, so is set to uniform 0 for convenience. In this case, as in most we encounter, the initial fields are set to be uniform.
The frontAndBack patch represents the front and back planes of the 2D case and therefore must be set as empty. As walls, both are given a zeroGradient boundary condition for p, meaning “the normal gradient of pressure is zero”. (see section 4.2.6 for more information) internalField the internal field data which can be uniform, described by a single value or nonuniform, where all the values of the field must be specified (see section 4.2.8 for more information) boundaryField the boundary field data that includes boundary conditions and data for all the boundary patches (see section 4.2.8 for more information).įor this case cavity, the boundary consists of walls only, split into 2 patches named: (1) fixedWalls for the fixed sides and base of the cavity (2) movingWall for the moving top of the cavity. There are 3 principal entries in field data files: dimensions specifies the dimensions of the field, here kinematic pressure, i.e. The mesh is generated by running blockMesh on this blockMeshDict file. The user is encouraged to consult section 5.3 to understand the meaning of the entries in the blockMeshDict file. The file first specifies coordinates of the block vertices it then defines the blocks (here, only 1) from the vertex labels and the number of cells within it and finally, it defines the boundary patches. For the remainder of the manual:įor the sake of clarity and to save space, file headers, including the banner and FoamFile sub-dictionary, will be removed from verbatim quoting of case files The file first contains header information in the form of a banner (lines 1-7), then file information contained in a FoamFile sub-dictionary, delimited by curly braces ( ).