6. Pressure loss study

6.1 Origin of pressure losses

Head losses during the movement of a real liquid or gas are caused by the irreversible transformation of the fluid's mechanical energy into heat. There are two aspects to pressure loss:

• friction losses (regular) ;

• singular losses.

Frictional head losses are caused by the viscosity (both molecular and turbulent) of real liquids and gases. They arise when there is movement, and result from an exchange of momentum between the molecules (laminar flow) or between the various particles (turbulent flow) of adjacent layers of liquid or gas moving at different speeds. These losses occur along the entire length of the pipe.

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