Explanation: Flow properties in the inlet should be known. If the flow properties are not known, it is good to move the boundary as far as possible from the region of interest.

Explanation: The convective flux of a property is a product of mass flow rate and the flow property. So, it can be easily obtained from the known values.

Explanation: The diffusive fluxes are usually not known. They should be approximated using the boundary values of the variables and one-sided finite difference approximations for the gradients.

Explanation: The grid extends outside the physical boundary and these nodes are used to store the inlet variables. The discretized equation is solved starting from the first internal cell.

Explanation: While calculating, the pressure field does not give absolute pressures. A reference pressure should be set before to resolve this problem. To set a reference pressure, absolute pressure is fixed at inlet node and pressure correction is set to zero there.

Explanation: The most accurate solutions can be achieved only if k and ε are specified at the inlet boundary. However, if it is not possible to provide, CFD codes can estimate these values using a formula.

Explanation: At the outlet, usually we know only little about the flow properties. For this reason, we should set the outlet boundary conditions as far as possible from the region of interest. Otherwise, error may propagate upstream.

Explanation: Pressure reference is set at the inlet boundaries and the link to the inlet side is suppressed. In the outlet boundaries, there is no need for setting another reference pressure but the link to the outlet side is suppressed.

Explanation: The theory of continuity (mass conservation) states that the inlet and outlet mass fluxes should be the same. So, they are always matched by some external calculations.