1D Manholes: Difference between revisions

When modelling conduit pipe flows, the head losses that the flow in pipe are subject to are made up of major losses (or friction losses) and minor losses (or local losses). Major losses are caused by forces between the flow and wetted perimeter of the conduit. Minor losses are caused by disruption to the flow due to bends, cross-sectional changes, fittings such as manholes and steps in the bed profile. Major losses are represented through the specification of a friction coefficient. The representation of minor losses, particularly for gravity networks, is at manholes and requires separate treatment. The default TUFLOW/Estry manhole loss approach uses the Engelund method explained in section 5.12.5.4 of the [https://downloads.tuflow.com/_archive/TUFLOW/Releases/2018-03/TUFLOW%20Manual.2018-03.pdf | TUFLOW user manual] although it is also possible to use a more simplified fixed manhole headloss approach too using the global <font color="blue"><tt>Manhole Default Loss Approach</tt></font> command or specifying within the '1d_mH_*' layer in the Loss_Approach attribute. The Engelund approach provides an automatic method for determining the loss coefficients as presented below. Of note is that the coefficients are recalculated every timestep, and therefore vary depending on the flow distribution between inlet and outlet conduits and the depth of water within the manhole. The losses represented are as follows: