Viscous Flow Questions & Answers  




You are absolutely right. It would have been more clear to take the partial derivative with respect to $x^\prime$. But the partial derivative with respect to $x$ is not affected by a change in reference frame, so this wouldn't change the end result.




The *mut contains $\mu_{\rm t}$ from the previous iteration (or from the initial condition if at the first iteration). Of course, for this to work, you need to update the coefficients and *mut within the function find_coeff_and_rhs().




It doesn't matter if $\mu_t$ is a long expression or not. Find it at the nodes first, and then calculate at the interfaces by taking the average of the nearby nodes. A simple approximation to $\partial u / \partial y$ is $(u_{j+1}u_{j1})/(2\Delta y)$. We'll see this tomorrow.




Did you check if your answer is gridconverged? I.e., if changing $N$ by 2 times does not result in a major change in $u_b$?



$\pi$ 