characterization of complex flows in the vicinity of … zurich 2016.pdf · icr 2012 aerc 2013 aerc...
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CHARACTERIZATION OF COMPLEX FLOWS IN THE VICINITY OF THE SEPARATION/STAGNATION POINTS
Iulia-Rodica Damian, Stefan Simionescu, Nicoleta-Octavia Tanase, Diana Broboana, Corneliu BalanREOROM - “Politehnica” University, Bucharest, Romania
Romanian Society Rheology
COMPUTATIONAL RHEOMETRY AN USEFUL TOOL TO ANALYSE
THE RHEOLOGICAL MEASUREMENTS
ICR 2012AERC 2013AERC 2014
Patterned lower plate
𝝎
RHEO-PATTBy 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 2016
10-2
10-1
100
101
102
103
104
105
10-2
10-1
100
101
102
Shea
r st
ress
[P
as]
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 2015ICR 2016
0,00000 0,00005 0,00010 0,00015 0,00020 0,00025
10-3
10-2
10-1
100
101
102
103
WSS < 0
DP
WS
S -
Wall
Shear
Str
ess
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
100
101
102
103
DPIP
- 1
0.0
0.2
0.7
1.0
Pre
ssu
re (
mo
du
le)
[Pa
]
y - wall direction
IP
SP
RHEOMETRY IN THE PRESENCEOF 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
pmax
pcr
Wal
l pre
ssu
re [
Pa]
pressure
x - wall direction
-1000
-800
-600
-400
-200
0
200
400
600
800
IP
wss
WSS
[P
a]
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
𝜂 𝛾 − 𝜂∞𝜂0 − 𝜂∞
= 1 + 𝜆 𝛾 2𝑛−12
𝜕𝑝
𝜕𝑥= 0𝜕3𝑝
𝜕𝑥3= 0
𝑝𝑐𝑟
𝑝𝑚𝑎𝑥
IP
SP
Experiments Numerics
ℛℯ < 10
𝑛 = 1 𝑛 = 0.7 𝑛 = 0.2 𝑛 = −1
𝑛 = 1𝑛 = −1
corner vortex
𝜔
𝜔IP
IP
𝑛 = 0.2 𝑛 = −1
upper rotational plate in vicinity of pillars
viscosity distributions on pillars surface
yconstant velocity
𝑛 = 1
𝑛 = −1
wall stresses distribution and location of critical points
x