MODELING GRAVITY-DRIVEN RIVULET ON A MONOTONICALLY VARYING INCLINE

2016 ◽  
Author(s):  
M. Isoz
Keyword(s):  
Gravity Driven

EFFECT OF FLOCCULATING AGENTS ON DRAG IN GRAVITY-DRIVEN FLOW SYSTEMS

2017 ◽  
Vol 44 (4) ◽  
pp. 339-347
Author(s):  
M. K. S. V. Raghav ◽  
Ravi Teja ◽  
Chirravuri Subbarao
Keyword(s):  
Flow Systems ◽  
Gravity Driven ◽  
Gravity Driven Flow

Drag reduction using mixed solutions of hydrotrope and surfactant in gravity driven flow systems

2013 ◽  
Vol 8 (3) ◽  
pp. 22-27
Author(s):  
M. Venkata Ramana ◽  
◽  
Ch. V. Subbarao ◽  
P. V. Gopal singh ◽  
Krishna Prasad K.M.M ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Mixed Solutions ◽  
Flow Systems ◽  
Gravity Driven ◽  
Gravity Driven Flow

Further Computational Investigations Into Aero-Engine Bearing Chamber Off-Take Flows

2010 ◽  
Author(s):  
Adam Robinson ◽  
Carol Eastwick ◽  
Herve´ Morvan
Keyword(s):  
Experimental Work ◽  
Symmetry Plane ◽  
Two Phase ◽  
Pipe System ◽  
Aero Engine ◽  
Gravity Driven ◽  
Computational Fluid Dynamics Cfd ◽  
Modelling Assumptions ◽  
Static Head ◽  
Engine Bearing

Within an aero-engine bearing chamber oil is provided to components to lubricate and cool. This oil must be efficiently removed (scavenged) from the chamber to ensure it does not overheat and degrade. Bearing chambers typically contain a sump section with an exit pipe leading to a scavenge pump. In this paper a simplified geometry of a sump section, here simply made of a radial off-take port on a walled inclined plane, is analysed computationally. This paper follows on work presented within GT2008-50634. In the previous paper it was shown that simple gravity draining from a static head of liquid cold be modelled accurately, for what was akin to a deep sump situation fond in integrated gear boxes for example. The work within this paper will show that the draining of flow perpendicular to a moving film can be modelled. This situation is similar to the arrangements found in transmission bearing chambers. The case modelled is of a walled gravity driven film running down a plane with a circular off-take port, this replicates experimental work similar to that reported in GT2008-50632. The commercial computational fluid dynamics (CFD) code, Fluent 6 [1] has been employed for modelling, sing the Volume of Fluid (VOF) approach of Hirt and Nichols [2, 3] to capture the physics of both the film motion and the two phase flow in the scavenge pipe system. Surface tension [4] and a sharpening algorithm [5] are used to complement the representation of the free surface and associated effects. This initial CFD investigation is supported and validated with experimental work, which is only depicted briefly here as it is mainly sued to support the CFD methodology. The case has been modelled in full as well as with the use of a symmetry plane running down the centre of the plane parallel to the channel walls. This paper includes details of the meshing methodology, the boundary conditions sued, which will be shown to be of critical importance to accurate modelling, and the modelling assumptions. Finally, insight into the flow patterns observed for the cases modelled are summarised. The paper further reinforces that CFD is a promising approach to analysing bearing chamber scavenge flows although it can still be relatively costly.

scholarly journals Well-Dispersed Silver Nanoparticles on Cellulose Filter Paper for Bacterial Removal

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 595
Author(s):  
Hsiu-Wen Chien ◽  
Ming-Yen Tsai ◽  
Chia-Jung Kuo ◽  
Ching-Lo Lin
Keyword(s):  
Silver Nanoparticles ◽  
Filter Paper ◽  
X Ray Diffraction ◽  
Bacterial Reduction ◽  
Treatment Technology ◽  
Bacterial Removal ◽  
Contaminated Drinking Water ◽  
Gravity Driven ◽  
Filter Papers ◽  
Cellulose Filter

In this study, a polydopamine (PDA) and polyethyleneimine (PEI)-assisted approach was developed to generate well-distributed PDA/PEI/silver (PDA/PEI/Ag) nanocomplexes on the surfaces of commercial cellulose filter papers to achieve substantial bacterial reduction under gravity-driven filtration. PDA can bind to cellulose paper and act as a reducer to produce silver nanoparticles (AgNPs), while PEI can react with oxidative dopamine and act as a dispersant to avoid the aggregation of AgNPs. The successful immobilization of PDA/PEI/Ag nanocomplexes was confirmed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were used as pathogen models to test the efficacy of the PDA/PEI/Ag nanocomplex-incorporated filter papers. The PDA/PEI/Ag nanocomplex-incorporated filter papers provided a substantial bacterial removal of up to 99% by simple gravity filtration. This work may be useful to develop a feasible industrial production process for the integration of biocidal AgNPs into cellulose filter paper and is recommended as a local-condition water-treatment technology to treat microbial-contaminated drinking water.

scholarly journals A numerical study of gravity-driven instability in strongly coupled dusty plasma. Part 1. Rayleigh–Taylor instability and buoyancy-driven instability

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Vikram S. Dharodi ◽  
Amita Das
Keyword(s):  
Dusty Plasma ◽  
Numerical Study ◽  
Fluid Model ◽  
Density Region ◽  
Strongly Coupled ◽  
Rising Bubble ◽  
Inhomogeneous Density ◽  
Gravity Driven ◽  
The Individual ◽  
Strongly Coupled Dusty Plasma

Rayleigh–Taylor (RT) and buoyancy-driven (BD) instabilities are driven by gravity in a fluid system with inhomogeneous density. The paper investigates these instabilities for a strongly coupled dusty plasma medium. This medium has been represented here in the framework of the generalized hydrodynamics (GHD) fluid model which treats it as a viscoelastic medium. The incompressible limit of the GHD model is considered here. The RT instability is explored both for gradual and sharp density gradients stratified against gravity. The BD instability is discussed by studying the evolution of a rising bubble (a localized low-density region) and a falling droplet (a localized high-density region) in the presence of gravity. Since both the rising bubble and falling droplet have symmetry in spatial distribution, we observe that a falling droplet process is equivalent to a rising bubble. We also find that both the gravity-driven instabilities get suppressed with increasing coupling strength of the medium. These observations have been illustrated analytically as well as by carrying out two-dimensional nonlinear simulations. Part 2 of this paper is planned to extend the present study of the individual evolution of a bubble and a droplet to their combined evolution in order to understand the interaction between them.

scholarly journals Gravity-Driven Membrane Reactor for Decentralized Wastewater Treatment: Effect of Reactor Configuration and Cleaning Protocol

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 388
Author(s):  
Ihtisham Ul Haq Shami ◽  
Bing Wu
Keyword(s):  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Economic Feasibility ◽  
Reactor Configuration ◽  
Membrane Performance ◽  
Decentralized Wastewater Treatment ◽  
Water Head ◽  
Cake Layer ◽  
Gravity Driven ◽  
Cleaning Protocol

In this study, three gravity-driven membrane (GDM) reactors with flat sheet membrane modules and various biocarriers (synthetic fibers, lava stones, and sands) were operated for municipal wastewater treatment. The effects of water head, periodically cleaning protocol, and operation temperature on the GDM reactor performance were illustrated in terms of membrane performance and water quality. The results indicated that: (1) the cake layer fouling was predominant (>~85%), regardless of reactor configuration and operation conditions; (2) under lower water head, variable water head benefited in achieving higher permeate fluxes due to effective relaxation of the compacted cake layers; (3) the short-term chemical cleaning (30–60 min per 3–4 days) improved membrane performance, especially when additional physical shear force was implemented; (4) the lower temperature had negligible effect on the GDM reactors packed with Icelandic lava stones and sands. Furthermore, the wastewater treatment costs of the three GDM reactors were estimated, ranging between 0.31 and 0.37 EUR/m3, which was greatly lower than that of conventional membrane bioreactors under lower population scenarios. This sheds light on the technical and economic feasibility of biocarrier-facilitated GDM systems for decentralized wastewater treatment in Iceland.

Sign in / Sign up

Export Citation Format

Share Document