Suppose a fluid passes from having laminar flow, to having a turbulent flow (like when passing after an object). How do fluid speed and fluid density change after that?

turbulent flow

  • $\begingroup$ I assume you mean the average speed and density, as the instantaneous values in a turbulent flow are highly complex and chaotic. Also, I think you need to be clearer about the flow situation: is this in a pipe? External flow? Is it incompressible/compressible? $\endgroup$ – Time4Tea Sep 27 at 11:19

In the case of pipe flow, the velocity remains constant simply through continuity, and the losses are influencing only to pressure. In the open channel flow the velocity depends on up- and downstream conditions, and can therefore even be higher after the object, but also lower if the object causes a hydraulic jump.

In the pipe flow the density is influenced only through the thermal expansion caused by the pressure turning to heat. In the open channel flow the density can change quite a lot if air entrainment occurs. The Turbulence has only indirect influence to density.

  • $\begingroup$ I assume here you are referring to the mean values? This answer seems to be assuming the flow is internal, within a pipe, which is not made clear in the question. Also, I'm not sure if open-channel flow is relevant - the effects of turbulence there may be very different to non-open flows. $\endgroup$ – Time4Tea Sep 27 at 11:21

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