Similarly, a constant rate at the right hand side, QR. would result in the following expression: 0²P 2x² 'N = P-P (4x)² QR AxAk +0(Ax) In a real reservoir case, flow rate conditions would normally represent production or injection rates for wells. A special case is the no-flow boundary, where Q = 0. This condition is specified at all outer limits of the reservoir, between non-communicating layers, and across sealing faults in the reservoir.