.FailureModes.NonlinearSolverFailures.InitialFailure .FailureModes.NonlinearSolverFailures.InitialFailureThis model describes a simple hydraulic system with a pump, followed by a valve, which fills a reservoir.
The initial value of the level of the reservoir is too high for the pump sizing, so the pressure p2 is too high and consequently the nonlinear algebraic system of equations that determines p1 and w_pump has no solution.
It is possible to find a solution to the system either by lowering the initial value of y, and thus the pressure p2, or by increasing the value of the parameter dp0, increasing the head the pump can provide.
The debugger should show the dependency of the nonlinear system of equations on the parameters dp0, a1, a2, a3, and Kv (also showing their values), as well as the dependency on p2 (which has a too high value). Once one understands that p2 is too high, it should be possible to continue the analysis, looking at the equation that determines p2, which in turn depends on the value of the state y, which is the root cause of the problem.
The nonlinear system that cannot be solved has five unknowns: w_pump, dp_pump, dp_valve, sqrt_dp, and p1, which can be easily reduced to one by using dp_pump as as a tearing variable. It should be possible to track the values of all five variables during the iterations of the Newton algorithm.