When creating direction changes in these lines consider the resultant drag caused by the abrupt change in the fluid's path as well as the turbulence it can create, which further affects the pressure and velocity values of the flowing fluid
The red pockets on the corners symbolize points of flow separation, which just means that the smooth stream is broken up into sections, causing turbulent flow and pressure losses.
All in all this just means that you should for as straight and consistent as a path as possible, and if you have to, utilize more gradual, smoother turns, as more abrupt and constant turning hurts fluid flow, leads to excess drag, as well as lots of pressure drops and turbulence

Topology Optimization

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