FLUID MECHANIC

                   Liquids or gas flow through pipes and ducts is commonly used in heating and cooling applicants ad fluid distribution networks.The fluid in such applications is usually forced to flow by a fan or pump through a flow section.We pay particular attention to friction, which directly related to pressure drop and head loss during flow through pipes and ducts.The pressure drop is used to determine the the pumping power requirement.A typical piping system involves pipes  of different diameter connected to each other by varaious fittings or elbows to route  the fluid,valves to control the flow rate, and pumps to pressurize the fluid.

 

                   The terms pipe, duct, and conduits are usually used interchangeably for flow sections.In general ,flow sections of circular cross section are referred  to as pipes(especially  when the fluid is liquid), and flow section of non-cicular  cross section as ducts(especially the fluid is gas).Small diameter pipes are usually referred to tubes. Most of fluids,especially liquids are transported in circular pipes.This is due to the pipes with a circular cross section can withstand large pressure differences between the inside and outside  without undergoing significant distortion.Non-cicular pipes are usually used in application such as the heating and cooling systems of buildings where the pressure  difference is relatively small,the manufacturing and installation costs are lower, and the available space is limited for ductwork.