42 results found
Craske J, Salizzoni P, van Reeuwijk M, The turbulent Prandtl number in a pure plume is 3/5, Journal of Fluid Mechanics, ISSN: 1469-7645
We derive a new expression for the entrainment coefficient in a turbulent plume usingan equation for the squared mean buoyancy. Consistency of the resulting expressionwith previous relations for the entrainment coefficient implies that the turbulent Prandtlnumber in a pure plume is equal to 3/5 when the mean profiles of velocity and buoyancyhave a Gaussian form of equal width. Entrainment can be understood in terms of thevolume flux, the production of turbulence kinetic energy or the production of scalarvariance for either active or passive variables. The equivalence of these points of viewindicates how the entrainment coefficient and the turbulent Prandtl and Schmidt numbersdepend on the Richardson number of the flow, the ambient stratification and the relativewidths of the velocity and scalar profiles. The general framework is valid for self-similarplumes, which are characterised by a power-law scaling. For jets and pure plumes it isshown that the derived relations are in reasonably good agreement with results fromdirect numerical simulations and experiments.
Krug D, Holzner M, Marusic I, et al., Fractal scaling of the turbulence interface in gravity currents, Journal of Fluid Mechanics, ISSN: 1469-7645
van Reeuwijk M, Krug D, Holzner M, Small-scale entrainment in inclined gravity currents, Environmental Fluid Mechanics, ISSN: 1567-7419
Bozovic R, Maksimovic C, Mijic A, et al., 2017, Blue Green Solutions. A Systems Approach to Sustainable and Cost-Effective Urban Development
This guide presents an innovative framework to systematically unlock the multiple benefits of city natural infrastructure; thus producing resilient, sustainable and cost-effective solutions. The framework is applicable at a building, neighbourhood and city-scale and is suitable both for new and retrofit developments.
Holzner M, van Reeuwijk M, 2017, The turbulent/nonturbulent interface in penetrative convection, JOURNAL OF TURBULENCE, Vol: 18, Pages: 260-270, ISSN: 1468-5248
Craske J, van Reeuwijk M, 2016, Generalised unsteady plume theory, JOURNAL OF FLUID MECHANICS, Vol: 792, Pages: 1013-1052, ISSN: 0022-1120
Schmidt L, Fouxon I, Krug D, et al., 2016, Clustering of particles in turbulence due to phoresis, PHYSICAL REVIEW E, Vol: 93, ISSN: 2470-0045
Suter I, Maksimović Č, van Reeuwijk M, 2016, A neighbourhood-scale estimate for the cooling potential of green roofs, Urban Climate, ISSN: 2212-0955
© 2017.Green roofs offer the possibility to mitigate multiple environmental issues in an urban environment. A common benefit attributed to green roofs is the temperature reduction through evaporation. This study focuses on evaluating the effect that evaporative cooling has on outdoor air temperatures in an urban environment. An established urban energy balance model was modified to quantify the cooling potential of green roofs and study the scalability of this mitigation strategy. Simulations were performed for different climates and urban geometries, with varying soil moisture content, green roof fraction and urban surface layer thickness. All simulations show a linear relationship between surface layer temperature reduction δT s and domain averaged evaporation rates from vegetation mmW, i.e. δT s = e W mmW, where e W is the evaporative cooling potential with a value of ∼-0.35 Kdaymm-1. This relationship is independent of the method by which water is supplied. We also derive a simple algebraic relation for e W using a Taylor series expansion.
van Reeuwijk M, Salizzoni P, Hunt GR, et al., 2016, Turbulent transport and entrainment in jets and plumes: A DNS study, PHYSICAL REVIEW FLUIDS, Vol: 1, ISSN: 2469-990X
Craske J, Debugne ALR, van Reeuwijk M, 2015, Shear-flow dispersion in turbulent jets, JOURNAL OF FLUID MECHANICS, Vol: 781, Pages: 28-51, ISSN: 0022-1120
Craske J, van Reeuwijk M, 2015, Energy dispersion in turbulent jets. Part 1. Direct simulation of steady and unsteady jets, JOURNAL OF FLUID MECHANICS, Vol: 763, Pages: 500-537, ISSN: 0022-1120
Craske J, van Reeuwijk M, 2015, Energy dispersion in turbulent jets. Part 2. A robust model for unsteady jets, JOURNAL OF FLUID MECHANICS, Vol: 763, Pages: 538-566, ISSN: 0022-1120
Morel CRG, van Reeuwijk M, Graf T, 2015, Systematic investigation of non-Boussinesq effects in variable-density groundwater flow simulations, JOURNAL OF CONTAMINANT HYDROLOGY, Vol: 183, Pages: 82-98, ISSN: 0169-7722
van Reeuwijk M, Craske J, 2015, Energy-consistent entrainment relations for jets and plumes, JOURNAL OF FLUID MECHANICS, Vol: 782, Pages: 333-355, ISSN: 0022-1120
van Reeuwijk M, Hadziabdic M, 2015, Modelling high Schmidt number turbulent mass transfer, INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW, Vol: 51, Pages: 42-49, ISSN: 0142-727X
van Reeuwijk M, Holzner M, 2014, The turbulence boundary of a temporal jet, JOURNAL OF FLUID MECHANICS, Vol: 739, Pages: 254-275, ISSN: 0022-1120
Craske J, van Reeuwijk M, 2013, Robust and accurate open boundary conditions for incompressible turbulent jets and plumes, COMPUTERS & FLUIDS, Vol: 86, Pages: 284-297, ISSN: 0045-7930
Jonker HJJ, van Reeuwijk M, Sullivan PP, et al., 2013, On the scaling of shear-driven entrainment: a DNS study, JOURNAL OF FLUID MECHANICS, Vol: 732, Pages: 150-165, ISSN: 0022-1120
Lari KS, van Reeuwijk M, Maksimovic C, 2013, The role of geometry in rough wall turbulent mass transfer, HEAT AND MASS TRANSFER, Vol: 49, Pages: 1191-1203, ISSN: 0947-7411
Lari KS, van Reeuwijk M, Maksimovic C, 2013, The role of geometry in rough wall turbulent mass transfer (vol 49, pg 1191, 2013), HEAT AND MASS TRANSFER, Vol: 49, Pages: 1523-1523, ISSN: 0947-7411
Jonker HJJ, Van Reeuwijk M, Sullivan PP, et al., 2012, Interfacial layers in clear and cloudy atmospheric boundary layers, 7th International Symposium on Turbulence, Heat and Mass Transfer, Publisher: International Centre for Heat and Mass Transfer
This paper reports on some recent advances in the understanding of the behaviour of atmosphericinterfacial layers. We focus on those interfaces where a turbulent layer is separated from a quiescentlayer by a relatively strong density gradient and study in particlar the entrainment rate, i.e. the rate withwhich the mixed layer penetrates into the quiescent layer by entraining fluid across the density interface.Making use of massively parallelized supercomputers, we conduct a large number of Direct NumericalSimulations (DNS) for a wide range of conditions and study the impact exerted on the entrainment rate bythe Reynolds number, the Prandtl/(Schmidt) number, and the strength of the density jump represented bythe Richardson number. We study two cases that are relevant for the atmosphere (/ocean), i.e. I] whereturbulence is generated by a surface buoyancy flux, and II] where turbulence is generated by shear (surfacemomentum flux). Of course with DNS one cannot simulate the high Reynolds numbers encountered in atmosphericcontexts, but present computer resources do allow us to faithfully simulate the classical laboratoryexperiments on these situations and even achieve Reynolds numbers more than ten times larger.
van Reeuwijk M, Lari KS, 2012, Asymptotic solutions for turbulent mass transfer at high Schmidt number, PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 468, Pages: 1676-1695, ISSN: 1364-5021
van Reeuwijk M, Lari KS, 2012, Asymptotic solutions for turbulent mass transfer augmented by a first order chemical reaction, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, Vol: 55, Pages: 6485-6490, ISSN: 0017-9310
Lari KS, van Reeuwijk M, Maksimovic C, et al., 2011, Combined bulk and wall reactions in turbulent pipe flow: decay coefficients and concentration profiles, JOURNAL OF HYDROINFORMATICS, Vol: 13, Pages: 324-333, ISSN: 1464-7141
van Reeuwijk M, 2011, A mimetic mass, momentum and energy conserving discretization for the shallow water equations, COMPUTERS & FLUIDS, Vol: 46, Pages: 411-416, ISSN: 0045-7930
van Reeuwijk M, Hunt GR, Jonker HJ, 2011, Direct simulation of turbulent entrainment due to a plume impinging on a density interface, 13th European Turbulence Conference (ETC), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Lari KS, van Reeuwijk M, Maksimovic C, 2010, Is using a plane-channel geometry to model wall-demand in turbulent pipe flow justified?, 10th International Conference on Computing and Control for the Water Industry, Publisher: CRC PRESS-TAYLOR & FRANCIS GROUP, Pages: 441-445
Lari KS, van Reeuwijk M, Maksimovic C, 2010, A study of wall demand in turbulent pipe flows, 10th International Conference on Computing and Control for the Water Industry, Publisher: CRC PRESS-TAYLOR & FRANCIS GROUP, Pages: 435-440
Lari KS, van Reeuwijk M, Maksimovic C, 2010, Simplified Numerical and Analytical Approach for Solutes in Turbulent Flow Reacting with Smooth Pipe Walls, JOURNAL OF HYDRAULIC ENGINEERING-ASCE, Vol: 136, Pages: 626-632, ISSN: 0733-9429
Mathias SA, Tsang C-F, van Reeuwijk M, 2010, Investigation of hydromechanical processes during cyclic extraction recovery testing of a deformable rock fracture, INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES, Vol: 47, Pages: 517-522, ISSN: 1365-1609
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