Flow type BC

When working with flow BC at the East side of the domain the first matrix index is k=2 as shown in (4.28) and (4.30). In addition, it's necessary to modify the previously calculated (4.18) coefficient D₂ as specified in (4.21). A₂ is not used. Here j₁ is the index of the first cell inside the domain, $u^{BC}_{i\;j_1}$ is the given BC velocity data. Such value is usually estimated as the flow (m³/s) divided by the cross section area.

$$D_2=D_2 + \frac{\Delta t}{2 \Delta x} H^n_{i\;j_1-1} u^{BC}_{i\;j_1}$$ (7.18)

$$D_{2m}=D_{2m} - \frac{\Delta t}{2 \Delta x} H^n_{i\;j_2} u^{BC}_{i\;j_2}$$ (7.19)