// Display mode mode(0); // Display warning for floating point exception ieee(1); clc; disp("Principles of Heat Transfer, 7th Ed. Frank Kreith et. al Chapter - 5 Example # 5.4 "); //''Ambient temp in degree C'' TinfinityC = 27; //''Ambient temp in degree K'' Tinfinity = TinfinityC+273; //''The criterion for transition is rayleigh number to be 10^9'' //''Value of coefficient of expansion at this temp in degree K inverse'' B = 1/Tinfinity; //''Value of Prandtl number at this ambient temp'' Pr = 0.71; //''Diameter of pipe in m'' D = 1; //''Value of kinematic viscosity at this temp in m2/s'' v = 0.0000164; //''acceleration due to gravity in m/s2'' g = 9.81; //''Therefore using Rayleigh number = ((Pr*g*B*deltaT*(D)^3)/v^2) = 10^9'' //''we get the temperature difference in centrigrade to be'' deltaT = 12; disp("therefore the temperature of pipe in C is") // temperature of pipe in C Tpipe = TinfinityC+deltaT //''From table 13 in Appendix 2, for the case of water and using the same procedure we get'' // temperature difference in C deltaTw = 0.05; disp("therefore the temperature of pipe in C is") // temperature of pipe in C Tpipew = TinfinityC+deltaTw disp(" Discussion - For air and water: ") disp(" Temperature required to induce turbulence is higher in air")