Effect of chain scission on flow characteristics of wormlike micellar solutions past a confined microfluidic cylinder: a numerical analysis

Soft Matter ◽  
2020 ◽  
Vol 16 (22) ◽  
pp. 5261-5272 ◽  
Author(s):  
Mohd Bilal Khan ◽  
C. Sasmal
Keyword(s):  
Numerical Analysis ◽  
Elastic Wave ◽  
Micellar Solution ◽  
Flow Characteristics ◽  
Chain Scission ◽  
Critical Value ◽  
Weissenberg Number ◽  
Elastic Instability ◽  
Micellar Solutions ◽  
Wave Phenomena

Elastic instability and elastic wave phenomena can be seen for the flow of a wormlike micellar solution past a confined microfluidic cylinder once the Weissenberg number exceeds a critical value.

scholarly journals Upstream vortex and elastic wave in the viscoelastic flow around a confined cylinder

2019 ◽  
Vol 864 ◽  
Author(s):  
Boyang Qin ◽  
Paul F. Salipante ◽  
Steven D. Hudson ◽  
Paulo E. Arratia
Keyword(s):  
Elastic Wave ◽  
Wave Speed ◽  
Three Dimensional ◽  
Weissenberg Number ◽  
Viscoelastic Flow ◽  
Absolute Instability ◽  
Elastic Instability ◽  
Cylinder Wake ◽  
Cylinder Axis ◽  
Flow Past A Cylinder

Viscoelastic flow past a cylinder is a classic benchmark problem that is not completely understood. Using novel three-dimensional (3D) holographic particle velocimetry, we report three main discoveries of the elastic instability upstream of a single cylinder in viscoelastic channel flow. First, we observe that upstream vortices initiate at the corner between the cylinder and the wall, and grow with increasing flow rate. Second, beyond a critical Weissenberg number, the flow upstream becomes unsteady and switches between two bistable configurations, leading to symmetry breaking in the cylinder axis direction that is highly 3D in nature. Lastly, we find that the disturbance of the elastic instability propagates relatively far upstream via an elastic wave, and is weakly correlated with that in the cylinder wake. The wave speed and the extent of the instability increase with Weissenberg number, indicating an absolute instability in viscoelastic fluids.

Experimental and Numerical Analysis of Mixing Process of Two Component Gases in a Vertical Fluid Layer in a VHTR

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Tetsuaki Takeda
Keyword(s):  
High Temperature ◽  
Natural Convection ◽  
Numerical Analysis ◽  
Pressure Vessel ◽  
Storage Tank ◽  
Molecular Diffusion ◽  
Flow Characteristics ◽  
Mixing Process ◽  
Two Component ◽  
Air Ingress

When a depressurization accident of a very-high-temperature reactor (VHTR) occurs, air is expected to enter into the reactor pressure vessel from the breach and oxidize in-core graphite structures. Therefore, in order to predict or analyze the air ingress phenomena during a depressurization accident, it is important to develop a method for the prevention of air ingress during an accident. In particular, it is also important to examine the influence of localized natural convection and molecular diffusion on the mixing process from a safety viewpoint. Experiment and numerical analysis using a three-dimensional (3D) computational fluid dynamics code have been carried out to obtain the mixing process of two-component gases and the flow characteristics of localized natural convection. The numerical model consists of a storage tank and a reverse U-shaped vertical rectangular passage. One sidewall of the high-temperature side vertical passage is heated, and the other sidewall is cooled. The low-temperature vertical passage is cooled by ambient air. The storage tank is filled with heavy gas and the reverse U-shaped vertical passage is filled with a light gas. The result obtained from the 3D numerical analysis was in agreement with the experimental result quantitatively. The two component gases were mixed via molecular diffusion and natural convection. After some time elapsed, natural circulation occurred through the reverse U-shaped vertical passage. These flow characteristics are the same as those of phenomena generated in the passage between a permanent reflector and a pressure vessel wall of the VHTR.

Numerical Analysis of Flow Characteristics for Intake Valve Design

2003 ◽  
Author(s):  
Duk-Sang Kim ◽  
Yeun-Jun Yoo ◽  
Yong-Seok Cho ◽  
In-Yong Ohm
Keyword(s):  
Numerical Analysis ◽  
Flow Characteristics ◽  
Intake Valve ◽  
Valve Design

Numerical analysis of the effect of the contraction rate of the curved hopper on flow characteristics of the silo discharge

2019 ◽  
Vol 356 ◽  
pp. 858-870 ◽  
Author(s):  
Hanru Liu ◽  
Fuguo Jia ◽  
Yawen Xiao ◽  
Yanlong Han ◽  
Gengrun Li ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Flow Characteristics ◽  
Contraction Rate ◽  
Silo Discharge
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