The boundary condition of the velocity inlet is specified at the
air inlet, and the boundary condition of pressure outlet is set
at the air outlet. The upper and front porous fibers are treated
as the wall where the air cannot pass through. Limited by the
computing resources, the thickness of FADS is set as 1 mm. The
no-slip condition is applied to all solid surfaces, and the standard
wall functions are adopted to link the solution variables at the
near-wall cells and the corresponding quantities near the wall.
Eqs. (1) and (2) are solved with the semi-implicit method using
pressure-linked equations-consistent (SIMPLEC) algorithm. The
computational domain is discretized by means of a structured
mesh. The convergence criterion of continuity, momentum, k and
ε equation are all set to be 10−3, with the convergence criteria for
energy equation set to be 10−6. In addition, during the whole simulation
process the quantities of airflow velocities and pressure at
several concerned points were dynamically monitored, until the
variations of these quantities with the iteration advancing became
all inappreciable. The final mesh is composed of 810,000 finite volumes.
The grid independent study is conducted. The map of mesh
grids on x = 1.1 m cross-section of FADS is shown in Fig. 2.