Forced convection from flat plate

Forced convection from flat plate

The function PlateNuT( ) is written to return either the laminar or mixed laminar/turbulent forced convection correlation results for isothermal surfaces depending on the value of Re_L. As an illustration, the influence of air speed on the convection coefficient of an isothermal plate can be investigated with PlateNuT( ) using the following commands:

Ts=50+273.15; Tinf=20+273.15; U=1; L=0.5; ReCrit=5e5;

load Air.dat

Tf = (Ts+Tinf)/2;

U = linspace(1,25,100);

[h NuL ReL] = PlateNuT(U,L,ReCrit,Air,Tf);

ax = plotyy(h,U,h,ReL);

axis(ax(1),[5 50 0 U(end)]);

axis(ax(2),[5 50 0 ReL(end)]);

Notice that at an air speed of U=16.4 m/s, the Reynolds number is at the transition value (rule of thumb) between laminar and turbulent flow for a smooth plate. Therefore, the convection coefficient is calculated from the laminar flow correlation at air speeds less than 16.4 m/s, while at greater speeds the mixed flow correlation is used.