# Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion

4.

In free convection heat transfer transition from laminar to turbulent flow is governed by the critical value of the

 [A]. Reynold's number [B]. Grashoff's number [C]. Reynold's number, Grashoff's number [D]. Prandtl number, Grashoff's number

Explanation:

No answer description available for this question.

 Sai Rama Prabhakar said: (Jun 7, 2013) In free convection the two dimensionless numbers are grashof's number & prandtl number where it is replaced by reynold's number & prandtl number for forced convection.

 Sanju said: (Nov 11, 2013) In free convection h is function of Pr number and Gr number. In forced convection h is function of Pr number and Re number.

 Sudheer said: (Jun 23, 2015) In free convection the two dimensionless numbers are Grashof's number & Prandtl numberwhere it is replaced by Reynold's number & Prandtl number for forced convection. In free convection h is function of Pr number and Gr number. Prandtl number, Grashoff's number. In forced convection h is function of Pr number and Re number.

 Sai Krishna said: (Jul 15, 2015) Would you please explain me Reynold's number, Grashof's number and Prandtl number?

 Rohit said: (Oct 1, 2015) Reynolds number = Re = Inertia forces/Viscous forces. Re = VD/v or (rho*V*D)/mu. Prandtl number = hl/k. Grashoff's number = (rho*g*B*l2*dt3)/mu.

 Ayyappa said: (Oct 27, 2015) In free convection Reynold's number matters. It is simply function of Grashoff's and prandtl.

 Amulraj said: (Apr 2, 2016) Refer heat and mass transfer data book CP Kothandraman. It contains all the formulas and relations.

 Gaurav said: (Dec 16, 2017) Critical value in free convection is Grashoff number only. Nusselt number is a function of GR No and PR No. So the answer should be B.

 Sreerag said: (Dec 24, 2017) @Rohit. I think Prandtl no = meu. Cp/k.

 Jonty said: (Aug 6, 2018) In free convection Nusselt number is a function of Re and Gr, on the other hand it is a function of Re and Pr for forced convection. So, answer C is correct.

 Kadam Vishal said: (Oct 8, 2018) According to me, Option A is also correct.