Preparation Write the Reynolds number. It represents the ratio of two forces. Wh
ID: 1996687 • Letter: P
Question
Preparation Write the Reynolds number. It represents the ratio of two forces. What are they? Under what conditions could the flow of a heavy fluid, such as oil, be considered an inviscid flow? Under what conditions can the flow of air be considered viscous? Write the equations of conservation of momentum and conservation of mass in integral form. Explain the meaning of each term. For the problem shown in Figure 1, reduce each equation to the simplest form. Be sure to state the assumptions used to reduce the equations. Using the mass and momentum equations, solve for the drag force, F_D (lbf), given the numbers in Figure 1. Assume the length of the cylinder is 8", or L = 0.667 ft. The height of the system is 7.5", or H = 0.625 ft. What is the cylinder Reynolds number for this problem (use U_1)? Is the flow laminar or turbulent? Using the Re, refer to the Figure in your text in chapter 9, and estimate the C_D Tor the cylinder. Using the drag force equation below, estimate the drag force on the cylinder for this case. Note than A_p is the projected (planform) area - Dia.*Length. F_D = 1/2 rho U_1^2 C_D A_pExplanation / Answer
Reynolds number (Re) is a dimensionless number that is used to predict whether a flow is laminar, turbulent or it’s in the transition zone.
Reynolds number is the ratio of inertial forces to viscous forces
Re = (density* velocity*characteristic length)/ (Dynamic viscosity)
Heavy fluids like oil lose their viscosity or become in viscid due to the following reasons:
Viscosity of air depends on Temperature. Above a critical transition air becomes becomes
Eg: At 15 °C, the viscosity of air is 1.81×105 kg/(m·s)