Quasi-static secondary flow regions formed by microfluidic contraction flows of wormlike micellar solutions

The electrooxidation of luminol in alkaline solutions in the presence of cetyltrimethylammonium bromide (I) was studied by linear sweep voltammetry on fixed and vibrating platinum electrodes. The presence of I in low concentrations (below the critical micellar concentration) brings about aggregation of the luminol, which is manifested by an increase in the anodic peak height and its shift towards lower potentials. In micellar solutions the peak height decreases owing to the slower diffusion of the bulkier micelles, the shift to lower potentials being preserved. The light-voltage curves correspond with the voltammetric curves, exhibiting identical shifts of the peak potentials in dependence on the concentration of the surfactant.

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Hydration of Aliphatic Aldehydes in Micellar Solutions

Materials Science Forum ◽

10.4028/www.scientific.net/msf.25-26.335 ◽

1988 ◽

Vol 25-26 ◽

pp. 335-338

Author(s):

Wilhelm Knoche ◽

Victoria R. Hanke ◽

Edward Dutkiewicz

Keyword(s):

Micellar Solutions ◽

Aliphatic Aldehydes

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A Review of Numerical Simulations of Secondary Flows in River Bends

Water ◽

10.3390/w13070884 ◽

2021 ◽

Vol 13 (7) ◽

pp. 884

Author(s):

Rawaa Shaheed ◽

Abdolmajid Mohammadian ◽

Xiaohui Yan

Keyword(s):

Numerical Modeling ◽

Numerical Simulations ◽

Secondary Flow ◽

Cross Section ◽

Turbulence Models ◽

Main Flow ◽

Secondary Flows ◽

River Bends ◽

River Cross Section ◽

River Bend

River bends are one of the common elements in most natural rivers, and secondary flow is one of the most important flow features in the bends. The secondary flow is perpendicular to the main flow and has a helical path moving towards the outer bank at the upper part of the river cross-section, and towards the inner bank at the lower part of the river cross-section. The secondary flow causes a redistribution in the main flow. Accordingly, this redistribution and sediment transport by the secondary flow may lead to the formation of a typical pattern of river bend profile. It is important to study and understand the flow pattern in order to predict the profile and the position of the bend in the river. However, there are a lack of comprehensive reviews on the advances in numerical modeling of bend secondary flow in the literature. Therefore, this study comprehensively reviews the fundamentals of secondary flow, the governing equations and boundary conditions for numerical simulations, and previous numerical studies on river bend flows. Most importantly, it reviews various numerical simulation strategies and performance of various turbulence models in simulating the flow in river bends and concludes that the main problem is finding the appropriate model for each case of turbulent flow. The present review summarizes the recent advances in numerical modeling of secondary flow and points out the key challenges, which can provide useful information for future studies.

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Structure and Interactions in Perfluorooctanoate Micellar Solutions Revealed by Small-Angle Neutron Scattering and Molecular Dynamics Simulations Studies: Effect of Urea

Langmuir ◽

10.1021/acs.langmuir.1c00433 ◽

2021 ◽

Vol 37 (17) ◽

pp. 5339-5347

Author(s):

Samhitha Kancharla ◽

Dengpan Dong ◽

Dmitry Bedrov ◽

Marina Tsianou ◽

Paschalis Alexandridis

Keyword(s):

Molecular Dynamics ◽

Neutron Scattering ◽

Molecular Dynamics Simulations ◽

Small Angle ◽

Small Angle Neutron Scattering ◽

Micellar Solutions ◽

Dynamics Simulations

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Secondary flow vortical structures in a 180∘ elastic curved vessel with torsion under steady and pulsatile inflow conditions

Physical Review Fluids ◽

10.1103/physrevfluids.3.013101 ◽

2018 ◽

Vol 3 (1) ◽

Cited By ~ 5

Author(s):

Mohammad Reza Najjari ◽

Michael W. Plesniak

Keyword(s):

Secondary Flow ◽

Vortical Structures ◽

Inflow Conditions

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Unsteady Flow Phenomena in Rotating Centrifugal Impeller Passages

Journal of Engineering for Power ◽

10.1115/1.3445302 ◽

1970 ◽

Vol 92 (1) ◽

pp. 65-71 ◽

Cited By ~ 25

Author(s):

E. Lennemann ◽

J. H. G. Howard

Keyword(s):

Unsteady Flow ◽

Secondary Flow ◽

Centrifugal Impeller ◽

Bubble Flow ◽

Hydrogen Bubble ◽

Visualization Technique ◽

Rotating Systems ◽

Flow Phenomena ◽

Relative Flow ◽

Zero Flow

The phenomena of unsteady relative flow observed in a centrifugal impeller passage running at part capacity and zero flow are discussed. The mechanisms of passage stall for a shrouded and unshrouded impeller are investigated and a qualitative correlation is developed for the influence of secondary flow and inducer flow on the passage stall. The hydrogen bubble flow visualization technique is extended to higher velocities and rotating systems and provides the method for obtaining the experimental results.

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