Experimental investigation of dryout phenomena under oscillatory flow conditions

Heat Transfer ◽  
2022 ◽  
Author(s):  
Rakesh Kumar ◽  
Dinesh K. Chandraker ◽  
Arnab Dasgupta ◽  
Arun K. Nayak
Keyword(s):  
Experimental Investigation ◽  
Oscillatory Flow ◽  
Flow Conditions

Modeling of mass transfer in biofilms in oscillatory flow conditions using k-ɛ turbulence model

2003 ◽  
Vol 3 (1-2) ◽  
pp. 201-207
Author(s):  
H. Nagaoka ◽  
T. Nakano ◽  
D. Akimoto
Keyword(s):  
Numerical Simulation ◽  
Mass Transfer ◽  
Turbulence Model ◽  
Uptake Rate ◽  
Oscillatory Flow ◽  
Substrate Uptake ◽  
Flow Conditions ◽  
Mass Transfer Mechanism ◽  
Substrate Uptake Rate ◽  
Good Agreement

The objective of this research is to investigate mass transfer mechanism in biofilms under oscillatory flow conditions. Numerical simulation of turbulence near a biofilm was conducted using the low Reynold’s number k-ɛ turbulence model. Substrate transfer in biofilms under oscillatory flow conditions was assumed to be carried out by turbulent diffusion caused by fluid movement and substrate concentration profile in biofilm was calculated. An experiment was carried out to measure velocity profile near a biofilm under oscillatory flow conditions and the influence of the turbulence on substrate uptake rate by the biofilm was also measured. Measured turbulence was in good agreement with the calculated one and the influence of the turbulence on the substrate uptake rate was well explained by the simulation.

EXPERIMENTAL INVESTIGATION OF DEBRIS DAMMING IN TRANSIENT FLOW CONDITIONS

2019 ◽  
Author(s):  
GABRIELLA MAUTI ◽  
JACOB STOLLE ◽  
IOAN NISTOR ◽  
MAJID MOHAMMADIAN
Keyword(s):  
Experimental Investigation ◽  
Transient Flow ◽  
Flow Conditions

Experimental investigation on the efficiency of a high side weir overflow

1999 ◽  
Vol 39 (2) ◽  
pp. 61-68 ◽  
Author(s):  
Gert Luyckx ◽  
Guido Vaes ◽  
Jean Berlamont
Keyword(s):  
Experimental Investigation ◽  
Settling Velocity ◽  
Scale Model ◽  
Flow Conditions ◽  
Sewer System ◽  
Side Weir ◽  
Sewer Systems ◽  
High Side ◽  
Sediment Fraction

Most of the overflow structures in Flanders are ‘high side weir overflows’. For the design of these structures British guidelines are used. However, the design conditions for sewer systems in the U.K. differ from the Flemish design conditions. In Flanders, pressurised flow is in common use in the pipes of the sewer system. That is why tests have been carried out on a scale model of a high side weir overflow. The optimal dimensions are determined, using different model sediments. Also efficiency relationships have been determined. For a particular chamber geometry and particular flow conditions, the efficiency of a certain sediment fraction is only determined by the settling velocity of this fraction.

scholarly journals Experimental Investigation of Ternary Al-Si-Cu Alloy Solidified with Unsteady-State Heat Flow Conditions

2018 ◽  
Vol 21 (3) ◽  
Author(s):  
Luis Antônio de Souza Baptista ◽  
Alexandre Furtado Ferreira ◽  
Késsia Gomes Paradela ◽  
Dimas Moraes da Silva ◽  
José Adilson de Castro
Keyword(s):  
Experimental Investigation ◽  
Heat Flow ◽  
Unsteady State ◽  
Flow Conditions ◽  
State Heat ◽  
Cu Alloy

Discovery of Side- and Shear-Dependent miRNAs and mRNAs in Human Aortic Valvular Endothelial Cells

2011 ◽  
Author(s):  
Casey J. Holliday ◽  
Randall F. Ankeny ◽  
Hanjoong Jo ◽  
Robert M. Nerem
Keyword(s):  
Endothelial Cells ◽  
Aortic Valve ◽  
Oscillatory Flow ◽  
Expression Profiles ◽  
Flow Conditions ◽  
Expression Of Genes ◽  
Inflammatory Phenotype ◽  
Cardiovascular Pathologies ◽  
Laminar Shear

Aortic valve (AV) disease is diagnosed by severe symptoms, such as calcification, and typically treated by AV replacement and repair surgeries. The mechanism by which AV disease occurs, specifically the role of the endothelium remains relatively unknown. It is known that disease preferentially occurs on the fibrosa, or aortic side, where it is exposed to disturbed, oscillatory flow, whereas the ventricularis, or side facing the left ventricle, experiences pulsatile, laminar shear and remains non-calcified [1, 2]. Research shows that regulation of miRNAs, short nucleotide segments targeting mRNAs, coincides with cardiovascular pathologies [3] though expression profiles of miRNAs and the mRNAs they modulate in human AV endothelial cells (HAVECs) have not been reported. We hypothesize that disturbed flow conditions present on the fibrosa stimulate ECs to modify expression of genes and miRNAs to induce a pro-inflammatory phenotype.

Unsteady flow about a sphere at low to moderate Reynolds number. Part 1. Oscillatory motion

1994 ◽  
Vol 277 ◽  
pp. 347-379 ◽  
Author(s):  
Eugene J. Chang ◽  
Martin R. Maxey
Keyword(s):  
Reynolds Number ◽  
Unsteady Flow ◽  
Steady Flow ◽  
Oscillatory Flow ◽  
Reynolds Numbers ◽  
Oscillatory Motion ◽  
Rigid Sphere ◽  
Flow Conditions ◽  
Steady Streaming ◽  
Moderate Reynolds Number

A direct numerical simulation, based on spectral methods, has been used to compute the time-dependent, axisymmetric viscous flow past a rigid sphere. An investigation has been made for oscillatory flow about a zero mean for different Reynolds numbers and frequencies. The simulation has been verified for steady flow conditions, and for unsteady flow there is excellent agreement with Stokes flow theory at very low Reynolds numbers. At moderate Reynolds numbers, around 20, there is good general agreement with available experimental data for oscillatory motion. Under steady flow conditions no separation occurs at Reynolds number below 20; however in an oscillatory flow a separation bubble forms on the decelerating portion of each cycle at Reynolds numbers well below this. As the flow accelerates again the bubble detaches and decays, while the formation of a new bubble is inhibited till the flow again decelerates. Steady streaming, observed for high frequencies, is also observed at low frequencies due to the flow separation. The contribution of the pressure to the resultant force on the sphere includes a component that is well described by the usual added-mass term even when there is separation. In a companion paper the flow characteristics for constant acceleration or deceleration are reported.

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