Scientific Results

This catalogue is obtained by conducting a systematic literature review of scientific studies and reviews related to monitoring, forecasting, and simulating the inland water cycle. The analysis maps scientific expertise across research groups and classifies findings by the type of inland water studied, application focus, and geographical scope. A gap analysis will identify missing research areas and assess their relevance to policymaking.

ID â–Č Type Year Authors Title Venue/Journal DOI Research type Water System Technical Focus Abstract Link with Projects Link with Tools Related policies ID
publications-1041 PEER_REVIEWED_ARTICLE 2017 Y. Zhou , J. C. Vassilicos Related self-similar statistics of the turbulent/non-turbulent interface and the turbulence dissipation 10.1017/jfm.2017.262 Uncategorized River Basins The scalings of the local entrainment velocity$v_{n}$of the turbulent/non-turbulent interface and of the turbulence dissipation rate are closely related to each other in an axisymmetric and self-similar turbulent wake. The turbulence dissipation scaling implied by the Kolmogorov equilibrium cascade phenomenology is consistent with a Kolmogorov scaling of$v_{n}$whereas the non-equilibrium dissipation scaling reported for various turbulent flows in Vassilicos (Annu. Rev. Fluid Mech., vol. 47, 2015, pp. 95–114), Dairayet al.(J. Fluid Mech., vol. 781, 2015, pp. 166–195), Goto & Vassilicos (Phys. Lett. A, vol. 379 (16), 2015, pp. 1144–1148) and Obligadoet al.(Phys. Rev. Fluids, vol. 1 (4), 2016, 044409) is consistent with a different scaling of $v_{n}$. We present results from a direct numerical simulation of a spatially developing axisymmetric and self-similar turbulent wake which supports this conclusion and the assumptions that it is based on. 320560
publications-1042 PEER_REVIEWED_ARTICLE 2016 K. Steiros , P. J. K. Bruce , O. R. H. Buxton , J. C. Vassilicos Power consumption and form drag of regular and fractal-shaped turbines in a stirred tank 10.1002/aic.15414 Uncategorized River Basins Previous wind‐tunnel measurements have shown that fractal‐shaped plates have increased drag compared to square plates of the same area. In this study, the power consumption and drag of turbines with fractal and rectangular blades in a stirred tank are measured. Power number decreases from rectangular to fractal impellers by over 10%, increasingly so with fractal iteration number. Our results suggest that this decrease is not caused by the wake interaction of the blades, nor solely by the wake interaction with the walls either. Pressure measurements on the blades’ surface show that fractal blades have lower drag than the rectangular ones, opposite to the wind tunnel experiment results. All tested blades’ center of pressure radius increases with Re, while their drag coefficient decreases, a possible effect of the solid body rotation expansion with Re. Spectral analysis of the pressure signal reveals two peaks possibly connected to the blades’ roll vortices. © 2016 American Institute of Chemical Engineers AIChE J, 63: 843–854, 2017 320560
publications-1043 PEER_REVIEWED_ARTICLE 2017 F. Alves Portela , G. Papadakis , J. C. Vassilicos The turbulence cascade in the near wake of a square prism 10.1017/jfm.2017.390 Data Management & Analytics River Basins We present a study of the turbulence cascade on the centreline of an inhomogeneous and anisotropic near-field turbulent wake generated by a square prism at a Reynolds number of$Re=3900$using the Kármán–Howarth–Monin–Hill equation. This is the fully generalised scale-by-scale energy balance which, unlike the Kármán–Howarth equation, does not require homogeneity or isotropy assumptions. Our data are obtained from a direct numerical simulation and therefore enable us to access all of the processes involved in this energy balance. A significant range of length scales exists where the orientation-averaged nonlinear interscale transfer rate is approximately constant and negative, indicating a forward turbulence cascade on average. This average cascade consists of coexisting forward and inverse cascade behaviours in different scale-space orientations. With increasing distance from the prism but within the near field of the wake, the orientation-averaged nonlinear interscale transfer rate tends to be approximately equal to minus the turbulence dissipation rate even though all of the inhomogeneity-related energy processes in the scale-by-scale energy balance are significant, if not equally important. We also find well-defined near$-5/3$energy spectra in the streamwise direction, in particular at a centreline position where the inverse cascade behaviour occurs for streamwise oriented length scales. 320560
publications-1044 PEER_REVIEWED_ARTICLE 2018 S. BaƟbuğ , G. Papadakis , J. C. Vassilicos Reduced power consumption in stirred vessels by means of fractal impellers 10.1002/aic.16096 Uncategorized Natural Water Bodies Earlier studies have shown that the power consumption of an unbaffled stirred vessel decreases significantly when the regular blades are replaced by fractal ones. In this paper, the physical explanation for this reduction is investigated using Direct Numerical Simulations at Re = 1600. The gaps around the fractal blade perimeter create jets that penetrate inside the recirculation zone in the wake and break up the trailing vortices into smaller ones. This affects the time‐average recirculation pattern on the suction side. The volume of the separation region is 7% smaller in the wake of the fractal blades. The lower torque of the fractal impeller is equivalent to a decreased transport of angular momentum; this difference stems from the reduced turbulent transport induced by the smaller trailing vortices. The major difference in the turbulent dissipation is seen in the vicinity of trailing vortices, due to fluctuations of velocity gradients at relatively low frequencies. © 2018 American Institute of Chemical Engineers AIChE J, 64: 1485–1499, 2018 320560
publications-1045 PEER_REVIEWED_ARTICLE 2018 I. Paul , G. Papadakis , J. C. Vassilicos Evolution of passive scalar statistics in a spatially developing turbulence 10.1103/physrevfluids.3.014612 Uncategorized River Basins No abstract available 320560
publications-1046 PEER_REVIEWED_ARTICLE 2018 G. Melina , P.J.K. Bruce , J. Nedić , S. Tavoularis , J.C. Vassilicos Heat transfer from a flat plate in inhomogeneous regions of grid-generated turbulence 10.1016/j.ijheatmasstransfer.2018.03.019 Data Management & Analytics Natural Water Bodies No abstract available 320560
publications-1047 PEER_REVIEWED_ARTICLE 2018 S. Srinath , J. C. Vassilicos , C. Cuvier , J.-P. Laval , M. Stanislas , J.-M. Foucaut Attached flow structure and streamwise energy spectra in a turbulent boundary layer 10.1103/physreve.97.053103 Uncategorized Natural Water Bodies No abstract available 320560
publications-1048 PEER_REVIEWED_ARTICLE 2011 L. Venema , D. von Terzi , H.-J. Bauer , W. Rodi DNS of heat transfer increase in a cylinder stagnation region due to wake-induced turbulence 10.1016/j.ijheatfluidflow.2011.03.003 Data Management & Analytics Natural Water Bodies No abstract available 320560
publications-1049 PEER_REVIEWED_ARTICLE 2018 Shaokai Zheng , P. J. K. Bruce , J. M. R. Graham , J. C. Vassilicos Weakly sheared turbulent flows generated by multiscale inhomogeneous grids 10.1017/jfm.2018.387 Data Management & Analytics River Basins A group of three multiscale inhomogeneous grids have been tested to generate different types of turbulent shear flows with different mean shear rate and turbulence intensity profiles. Cross hot-wire measurements were taken in a wind tunnel with Reynolds number$Re_{D}$of 6000–20 000, based on the width of the vertical bars of the grid and the incoming flow velocity. The effect of local drag coefficient$C_{D}$on the mean velocity profile is discussed first, and then by modifying the vertical bars to obtain a uniform aspect ratio the mean velocity profile is shown to be predictable using the local blockage ratio profile. It is also shown that, at a streamwise location$x=x_{m}$, the turbulence intensity profile along the vertical direction$u^{\prime }(y)$scales with the wake interaction length$x_{\ast ,n}^{peak}=0.21g_{n}^{2}/(\unicode[STIX]{x1D6FC}C_{D}w_{n})$($\unicode[STIX]{x1D6FC}$is a constant characterizing the incoming flow condition, and$g_{n}$,$w_{n}$are the gap and width of the vertical bars, respectively, at layer$n$) such that$(u^{\prime }/U_{n})^{2}\unicode[STIX]{x1D6FD}^{2}(C_{D}w_{n}/x_{\ast ,n}^{peak})^{-1}\sim (x_{m}/x_{\ast ,n}^{peak})^{b}$, where$\unicode[STIX]{x1D6FD}$is a constant determined by the free-stream turbulence level,$U_{n}$is the local mean velocity and$b$is a dimensionless power law constant. A general framework of grid design method based on these scalings is proposed and discussed. From the evolution of the shear stress coefficient$\unicode[STIX]{x1D70C}(x)$, integral length scale$L(x)$and the dissipation coefficient$C_{\unicode[STIX]{x1D716}}(x)$, a simple turbulent kinetic energy model is proposed that describes the evolution of our grid generated turbulence field using one centreline measurement and one vertical profile of$u^{\prime }(y)$at the beginning of the evolution. The results calculated from our model agree well with our measurements in the streamwise extent up to$x/H\approx 2.5$, where$H$is the height of the grid, suggesting that it might be possible to design some shear flows with desired mean velocity and turbulence intensity profiles by designing the geometry of a passive grid. 320560
publications-1050 PEER REVIEWED ARTICLE 2018 Thomas A. Davidson , Joachim Audet , Erik Jeppesen , Frank Landkildehus , Torben L. Lauridsen , Martin SÞndergaard , Jari SyvÀranta Synergy between nutrients and warming enhances methane ebullition from experimental lakes 10.1038/s41558-017-0063-z Data Management & Analytics River Basins No abstract available 603378