Knowledge Base

Found 4 Results

Article

High Schmidt number “Washout” of a soluble contaminant downstream of a backward-facing step

Min, D., Fischer, P.F., Pearlstein, A.J.

2020Intl. J. Heat Mass Transfer159119740

Keywordscavity flow, cleaning, mass transfer

DisciplinesChemical Engineering, Fluid Mechanics, Mechanical Engineering

Non-expert summaryThis is a dynamic simulation of removal of a soluble component by diffusive mass transfer from the shadow region of a 2-D backward facing step. The scenario is this: a fully developed laminar flow (Reynolds number of 10 and 100) between two parallel plates encounters a shallow 90 degree step in the lower plate (the step height is 0.02 x the initial duct height). A nonreactive soluble component is present in the region next to the step, essentially a square of contaminated fluid. The washout of this packet of fluid, by flow over the step and diffusion, is modelled for Schmidt numbers between 7 and 2650. Streamlines and contentration contours over time are mapped and characteristic timescales are computed. The results will be of interest to those interested in the washout of contaminated liquids in shallow recesses.

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Article

Experimental investigation of laminar and turbulent displacement of residual oil film

Zhang, Y., Barrouillet, B. and Skadsem, H.J.

2023Scientific Reports1321120

Keywordscleaning, flow displacement, shear flow, thin film

DisciplinesChemical Engineering, Fluid Mechanics, Mechanical Engineering

CategoryLaboratory experiments

Scale1e-6 to 1e-3 m / 1 to 60 s

Non-expert summaryThis paper reports an experimental study of the removal of thin oil films from the wall of a cylindrical tube by a flow of water. The removal of the oil film is measured by monitoring dye concentration in the flushing liquid leaving the system: local extents of removal were not measured. The authors investigated the effect of the flow regime of the displacing fluid (water Reynolds numbers ranged from 1480 to 12690), the duration of the displacing fluid flow, and the estimated wall shear stress imposed on the film. When the volume of fluid is limited, the largest displacement efficiency was observed at Re = 7000-8000 (named the intermediate turbulent regime). The largest Reynolds number flows were most effective for achieving complete cleaning over a long time period.

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Article

Self-cleaning of a hydrophobic surface by a rolling water droplet

Hassan, G., Yilbas, B.S., Al-Sharafi, A., Al-Qahtani, H.

2019Scientific Reports95744

Keywordscleaning, drop, flow displacement, wetting

DisciplinesMechanical Engineering, Surface Chemistry

CategoriesLaboratory experiments, Theoretical modelling

Scale1e-6 to 1e-3 m, 1e-3 m, 1e-3 to 1 m / 1e-3 to 1 s, 1 to 60 s

Non-expert summaryThis is an experimental study of removal of dust particles from a hydrophobic surface by a rolling/sliding water droplet. The effect of surface inclination angle on droplet dynamics and dust removal is analyses and compared with a model. Droplet rolling dominates over sliding. Removal is mainly due to the droplet liquid coating the particles as it passes over the particle, and the removal efficiency is determined by the inclination of the surface.

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Review article

Liquid jet impingement

Lienhard, J.H.

1995Annual Review of Heat Transfer6199-270

Keywordscleaning, heat transfer, multiphase flow

DisciplinesFluid Mechanics, Mechanical Engineering

CategoryReview

Scale1e-6 to 1e-3 m, 1e-3 to 1 m / 1e-3 to 1 s, 1 to 60 s

Non-expert summaryThis is a review of heat transfer and flow phenomena during unsubmerged liquid jet impingement on solid surfaces, such as when a water jet passes through air and impinges on a wall. Both axisymmetric and planar jets are considered. The focus is on convective transport without phase change. Results for the stagnation zone are given first, followed by those for the regions downstream. Correlations are presented for flow and heat transfer phenomena. The heat fluxes that can be generated in these systems can be large, so there is a considerable body of work on topic. Splattering - the formation of breakaway droplets from the liquid film - that accompanies turbulent jet impingement is described. Other aspects of liquid jet impingement cooling are discussed briefly.

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