A water jet strikes a cylindrical rod of radius head-on with outer stream speed far…

PHYSICS · Subjective · Fermi University Physics · Fluids & Continuum Physics · Viscous flow and dynamical similarity · Viscous flow and dynamical similarity

Fluid Dynamics, Ch The Navier-Stokes equations and unsteady exact solutions

Problem

A water jet strikes a cylindrical rod of radius a=3.0 cma = 3.0\,\mathrm{cm} head-on with outer stream speed U=2.0 m s−1U = 2.0\,\mathrm{m\,s^{-1}} far from the rod. Near the nose the outer flow behaves as Hiemenz stagnation-point flow with strain rate S=2U/aS = 2U/a. Water has ρ=998 kg m−3\rho = 998\,\mathrm{kg\,m^{-3}} and μ=1.00×10−3 Pa s\mu = 1.00\times10^{-3}\,\mathrm{Pa\,s}. Find the thickness of the layer near the nose within which the flow is within one per cent of the outer flow.

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