ESR CHARACTERIZATION OF COMPLEX FLOWS IN THE VICINITY OF THE SEPARATION/STAGNATION POINTS Iulia-Rodica Damian, Stefan Simionescu, Nicoleta-Octavia Tanase, Diana Broboana, Corneliu Balan REOROM - “Politehnica” University, Bucharest, Romania Romanian Society Rheology COMPUTATIONAL RHEOMETRY AN USEFUL TOOL TO ANALYSE THE RHEOLOGICAL MEASUREMENTS ICR 2012 AERC 2013 AERC 201 4 Patterned lower plate RHEO - PATT By REOROM Rheometry of complex fluids in presence of patterned surfaces Exploratory Research Projects PCE The locations on solid surfaces of the critical points: impact point – IP and separation point – SP, where WSS = 0, are related with the wall pressure distribution; the influence of the shear thinning viscosity. 20th Anniversary Meeting of the European Society of Rheology 01 April, ETH Zürich 201 6 10 -2 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 -2 10 -1 10 0 10 1 10 2 Shear stress [Pas] Shear rate [1/s] n - value [-] - 1.0 - 0.1 0.0 0.2 0.7 1.0 unstable model for n < 0 0 AERC 2015 ICR 201 6 0,00000 0,00005 0,00010 0,00015 0,00020 0,00025 10 -3 10 -2 10 -1 10 0 10 1 10 2 10 3 WSS < 0 DP WSS - Wall Shear Stress y - wall direction - 1 0.0 0.2 0.7 1.0 IP WSS < 0 0,00000 0,00005 0,00010 0,00015 0,00020 0,00025 10 -2 10 -1 10 0 10 1 10 2 10 3 DP IP - 1 0.0 0.2 0.7 1.0 Pressure (module) [Pa] y - wall direction IP SP RHEOMETRY IN THE PRESENCE OF PATTERNED AND MICROSTRUCTURED SURFACES Tested Carreau viscosity function VORTICES FORMATION IN THE VICINITY OF PATTERNED SURFACES WITH CAVITIES AND PILLARS 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 p max p cr Wall pressure [Pa] pressure x - wall direction -1000 -800 -600 -400 -200 0 200 400 600 800 IP wss WSS [Pa] IP IP IP SP IP and SP in the Taylor-Couette flow (iso-pressure and stream lines) Poiseuille flow in a channel stream lines iso-pressure − ∞ 0 − ∞ = 1+ 2 −1 2 =0 3 3 =0 IP SP Experiments Numerics ℛℯ < 10 =1 = 0.7 = 0.2 = −1 =1 = −1 corner vortex IP IP = 0.2 = −1 u pper rotational plate in vicinity of pillars viscosity distributions on pillars surface y constant velocity =1 = −1 wall stresses distribution and location of critical points x