Numerical Simulation of Drag Reducing Flow by Polymer Additives Using Equilibrium Dumbbell Element Model
Details
A model to simulate the drag reduction by dilute addition of polymer or surfactant (Toms effect) is proposed based on the discrete element model. The dimension of the discrete element, which represents the polymer or the rod-like micelle, is very small compared to that of the velocity fluctuation of the fluid. So it is assumed that the element is in equilibrium state in the fluid and turns to the direction of an eigenvector of the velocity gradient tensor. And the macroscopic effect of the discrete elements is modeled as the stress assuming the elements are independent each other. Direct numerical simulations are carried out with this new model using the rigid dumbbell element as a discrete element model and it is shown that the drag reduction up to 37% drag reduction rate is reproduced. The mechanism of the drag reduction is discussed based on the DNS database.
