scholarly journals Steady flow regimes and mixing performance in arrow-shaped micro-mixers

2019 ◽  
Vol 4 (3) ◽  
Author(s):  
A. Mariotti ◽  
C. Galletti ◽  
E. Brunazzi ◽  
M. V. Salvetti
Keyword(s):  
Steady Flow ◽  
Flow Regimes ◽  
Mixing Performance

Mathematical modeling of Couette flow in anomalous thermoviscous liquid

2011 ◽  
Vol 8 (1) ◽  
pp. 143-152
Author(s):  
S.F. Khizbullina
Keyword(s):  
Mathematical Modeling ◽  
Angular Velocity ◽  
Numerical Experiment ◽  
Temperature Dependence ◽  
Steady Flow ◽  
Couette Flow ◽  
Outer Cylinder ◽  
Flow Regimes ◽  
Constant Angular Velocity ◽  
Coaxial Cylinders

The steady flow of anomalous thermoviscous liquid between the coaxial cylinders is considered. The inner cylinder rotates at a constant angular velocity while the outer cylinder is at rest. On the basis of numerical experiment various flow regimes depending on the parameter of viscosity temperature dependence are found.

Flow Over Two Circular Disks in Tandem

1980 ◽  
Vol 102 (1) ◽  
pp. 104-111 ◽  
Author(s):  
T. Morel ◽  
M. Bohn
Keyword(s):  
Drag Reduction ◽  
Steady Flow ◽  
Unsteady Flows ◽  
Flow Regimes ◽  
Diameter Ratio ◽  
Bluff Bodies ◽  
Steady Flows ◽  
Near Wake ◽  
Total Drag ◽  
Circular Disks

Placing two or more bluff-bodies in tandem is known to lead, in some cases, to configurations with relatively low overall drag. The present study concerns one particular case where two disks of unequal diameters, normal to the flow, are placed in tandem for the purpose of drag reduction. It shows that very significant drag reductions may be achieved by proper sizing of the disk diameters and of the gap between them. Placing a properly sized disk at an optimum distance ahead of a single reference disk can result in a configuration whose total drag is up to 81 percent lower than that of the reference disk alone. If the additional disk is placed behind into the near-wake of the reference disk, the drag of the two-disk configuration can be up to 70 percent lower than for the reference disk alone. Four different flow regimes have been identified, depending on the diameter ratio of the two disks, two with relatively steady flows and two with unsteady flows. The absolute drag minimum was found to occur in one of the two steady-flow regimes.

Flow regimes and mixing performance in T-T jet reactor

2021 ◽  
pp. 108700
Author(s):  
Haiyan Bie ◽  
Licheng Xue ◽  
Yue Wang ◽  
Gang Liu ◽  
Zongrui Hao ◽  
...  
Keyword(s):  
Flow Regimes ◽  
Mixing Performance

Experimental and Numerical Analyses of Unsteady Flow Regimes and Mixing in a Micro T-Mixer

2018 ◽  
Author(s):  
Maria Vittoria Salvetti ◽  
Alessandro Mariotti ◽  
Chiara Galletti ◽  
Elisabetta Brunazzi
Keyword(s):  
Mirror Symmetry ◽  
Three Dimensional ◽  
Flow Regimes ◽  
Dramatic Decrease ◽  
Mixing Performance ◽  
Numerical Predictions ◽  
Simple Geometry ◽  
Periodic Dynamics ◽  
High Degree ◽  
Unsteady Regimes

Despite the very simple geometry, T-shaped micro-mixers are characterized by different and complex laminar flow regimes. In the present work, experiments and direct numerical simulations are employed jointly to investigate unsteady periodic flow regimes, viz. the asymmetric and symmetric regimes. The first is characterized by a periodic dynamics of the three-dimensional structures and by a high degree of mixing, while in the second the flow always maintains a double mirror symmetry in the mixing channel, which causes a dramatic decrease of the mixing performance. A methodology, allowing us to quantitatively compare the numerical predictions with experimental flow visualizations, is used to investigate these unsteady regimes and to evaluate the relevant frequencies and the degree of mixing. In both regimes the characteristic non-dimensional frequency, based on the bulk velocity and hydraulic diameter of the mixing channel, increases with the Reynolds number, but a significant discontinuity is found at the transition from the first to the second regime.

Laminar Flow Over Wavy Walls

1991 ◽  
Vol 113 (4) ◽  
pp. 574-578 ◽  
Author(s):  
V. C. Patel ◽  
J. Tyndall Chon ◽  
J. Y. Yoon
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
Steady Flow ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Flow Regimes ◽  
Navier Stokes ◽  
Wavy Wall ◽  
Fully Developed Flow ◽  
Navier Stokes Equations

The boundary layer over a wavy wall and fully-developed flow in a duct with a wavy wall are considered. Numerical solutions of the Navier-Stokes equations have been obtained to provide insights into the various steady flow regimes that are possible, and to illustrate the nuances of predicting flows containing multiple separation and reattachment points.

Steady and Unsteady Airflow Through the Intake Valve of a Reciprocating Engine

1985 ◽  
Vol 107 (3) ◽  
pp. 413-420 ◽  
Author(s):  
A. F. Bicen ◽  
C. Vafidis ◽  
J. H. Whitelaw
Keyword(s):  
Flow Pattern ◽  
Steady Flow ◽  
Laser Doppler Anemometry ◽  
Flow Regimes ◽  
Residual Effects ◽  
Mean Flow ◽  
Flow Angle ◽  
Flow Unsteadiness ◽  
Reciprocating Engine ◽  
Valve Operation

An experimental investigation of the airflow through various axisymmetric intake ports of a motored reciprocating engine is reported. Detailed velocity field measurements obtained by laser Doppler anemometry and for steady and various unsteady flow conditions are presented together with valve discharge coefficients from steady flow tests. The results showed that over the lift range investigated the valve flow exhibited various regimes indicated by the changes in the flow pattern at the valve exit. With a 45-deg seat angle, four regimes were identified compared to three in the case of a 60-deg valve. The overall behavior of the 45-deg valve, however, was found to be generally better. Rounding of the edges of the 45-deg valve reduced the number of flow regimes to two with marked improvements on discharge coefficient. The flow angle at the valve exit depended less on the flow regimes and more on the cylinder confinement, in the absence of which the transition from one regime to another was delayed. The mean flow pattern at the valve exit was found to be insensitive to flow unsteadiness, piston confinement and valve operation and thus could be predicted with reasonable accuracy from steady flow tests. The in-cylinder flow characteristics were also insensitive to valve operation, but strongly depended on piston interaction, flow unsteadiness and residual effects from the previous cycle.

Reduction/Suppression of VIV of Circular Cylinders Through Roughness Distribution at 8×103 < Re < 1.5×105

2008 ◽  
Author(s):  
Michael M. Bernitsas ◽  
Kamaldev Raghavan
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Circular Cylinder ◽  
Steady Flow ◽  
Flow Regimes ◽  
Grit Size ◽  
Circular Cylinders ◽  
Vortex Induced Vibration

Vortex Induced Vibration (VIV) of a circular cylinder in a steady flow is reduced using distributed surface roughness. VIV reduction is needed in numerous applications where VIV is destructive. Roughness is distributed to the surface of the cylinder in the form of sandpaper strips to achieve three goals: (1) Trip separation in a controlled manner so that some uncertainties are removed and the flow becomes more predictable. (2) Reduce spanwise correlation, which is strongly linked to VIV. (3) Select roughness grit size to achieve the first goal without energizing too much the boundary layer, which would induce higher vorticity and circulation, and consequently lift. Our experiments show that it is possible to reduce VIV amplitude and synchronization range. More tests are needed to achieve full suppression. Our experiments are conducted in the TrSL2 and TrSL3 flow regimes.

Sign in / Sign up

Export Citation Format

Share Document