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B In control volume analysis, why kinetic energy and flow work are considered seperately?

  1. Jun 14, 2018 #1
    As per work energy principle, the energy spent in moving an object is stored as kinetic energy.Flow work is done to make the fluid move.Why is it not included in kinetic energy (i.e) why kinetic energy and flow work are considered seperately?
     
  2. jcsd
  3. Jun 15, 2018 #2
    the flow of liquids are a bit complicated due to internal energy changes , may be temperature change, viscous forces as well as the

    molecular motions, i think a detail energy analysis is required. and one can not simply equate the work done to the K.E. of the flow.

    The forces that act on the surface of a control volume do work on the fluid in the control volume and therefore contribute to the energy

    balance. The power (energy per second) put into the fluid within the control volume is given by the classical relation from mechanics P ower input to the control volume = F - U

    there is an interesting analysis in the following reference-

    <https://web.stanford.edu/~cantwell/...ls_of_Compressible_Flow_Ch_01_BJ_Cantwell.pdf>
     
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