Hi everyone,
I am working on natural convection.
I try to analysis one model using ansys fluent. For this model, Prandtl number was determined is equal to one. I am working 25 degrees celcius in standart conditions.
How can I determine fluid properties for prandtl number is equal to one.
I mean for example, 0.71 is used for air in 25 degrees celcius. I want to study 25 degrees celcius conditions but when prandtl number is equal to one. Then it is not compatible with conditions.
Typhoon; Which is your domain of interest?
If it's a flat plate, then Pr =1 (air), then delta_hydroBL=delta_thermalBL= 5*x/pow(Re, 0.5). For this you can have two cases; 1) fix a delta_hydroBL and x is the length of plate (which is already fixed as per ur model) and then find Re 2) Fix an Re and then find BL
After that you can use local heat transfer coefficient, h = 0.332*pow(Re,0.5)*pow(Pr,0.33)
Then you know, Q/A = -k*dt/dx = h*(Ts-Tinf) ; then you can fix a Q value to find Ts within a permissible range. In short if you know Ts, you can randomly use the properties based on Ts+25 degree/2 to get more or less the same result at Pr =1.
Note: I dont know, if its applicable like this in your case or if it is right to do this way (it's just a suggestion)
Thank you for your answer. I mean for example rayleigh=10^7 and prandtl=1
What is the value of cp,thermal conductivity, density vs.
and second question for rayleigh number is equal to 10^7
ra=(ro*beta*deltaT*Lref^3)/(kinematics viscosity*alfa)
ro, beta, kinematics viscosity and alfa is constant. I specified Lref=1 m
Then deltaT is equal to 760. But I am working on natural convection in square cavity.
Result is not good.
How to overcome this problem.
Thank you in advance.
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