What is Flow split at a branch?

How a flow divides when one pipe branches into two. It settles where the pressures balance.

A longer or narrower branch takes less of the flow. To know whether each branch gets enough, the split has to be calculated.

Open two taps at once and the one at the end of a longer hose runs weaker.

A Splitter either takes the split as a fraction or solves it from the pressures. When solving, it finds the split at which both branches end at their boundary pressures (or at equal pressure where they merge again), calculating every pipe and block of both branches.

For the fraction x going to branch 1, it finds where the pressure surplus at the end of each branch, s_i = p_{\mathrm{end},i} - p_{\mathrm{boundary},i}, is the same:
s_1(x\,\dot{m}) = s_2((1-x)\,\dot{m})
Each s falls monotonically as its flow rises, so the solution is unique. A negative common surplus means the inlet pressure is not enough.

In V1 each branch must be a chain of pipes, heaters and reactors ending at outlets (both with a boundary pressure or both without) or at one common mixer. Reverse flow is not modeled.

• Mass flow rate
• Pressure loss
• Loss coefficient (K)
• Pipe pressure loss calculation