The discussion focuses on calculating surface shear stress in a boundary layer with a given velocity profile defined by the equation v = ay + by², where the dynamic viscosity is 18x10-6 kg/ms. Participants worked through the calculation of shear stress using the formula τ = μ(du/dy) and attempted to derive constants a and b from velocity measurements at specified distances from the surface. The correct surface shear stress was identified as 1.17 N/m², contrasting with initial incorrect calculations of 0.36 N/m² and 0.9 N/m². The final consensus confirmed that a = 65000/sec is necessary for accurate results.
PREREQUISITESStudents and professionals in fluid mechanics, mechanical engineers, and anyone involved in the analysis of boundary layer behavior and shear stress calculations in fluid dynamics.
I have tried the differences of the velocities and distance (du/dy) . Then multiplied it by the dynamic viscosity which came out as 0.36 N/m^2 but the answer is apparently 1.17 N/m^2.Chestermiller said:What have you figured out so far?
You need to solve for a and b from the velocity data; a is the shear rate at the wall.exphaze said:I have tried the differences of the velocities and distance (du/dy) . Then multiplied it by the dynamic viscosity which came out as 0.36 N/m^2 but the answer is apparently 1.17 N/m^2.
I have worked out a = 50000 and substituted to τ*shear rate =μ and this came out as 0.9 N/m^2. I am still stuck.Chestermiller said:You need to solve for a and b from the velocity data; a is the shear rate at the wall.
I get a = 65000/secexphaze said:I have worked out a = 50000 and substituted to τ*shear rate =μ and this came out as 0.9 N/m^2. I am still stuck.
I got it now, Thanks for the advice!Chestermiller said:I get a = 65000/sec