For a fluid with a prandtl number of 1000.0, the hydrodynamic layer is thinner than the thermal boundary layers. a) true b) false

(b)False

Explanation:

Given:

 Prandtl number(Pr) =1000.

We know that  

  Where is the molecular diffusivity of momentum

              is the molecular diffusivity of heat.

 Prandtl number(Pr) can also be defined as

Where is the hydrodynamic boundary layer thickness and is the thermal boundary layer thickness.

So if Pr>1 then hydrodynamic boundary layer thickness will be greater than thermal boundary layer thickness.

In given question Pr>1 so  hydrodynamic boundary layer thickness will be greater than thermal boundary layer thickness.

So hydrodynamic layer will be thicker than the thermal boundary layer.

1

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