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-1021 PEER REVIEWED ARTICLE 2013 Hjalmar Laudon , Ida Taberman , Anneli Ågren , Martyn Futter , Mikaell Ottosson-Löfvenius , Kevin Bishop The Krycklan Catchment Study-A flagship infrastructure for hydrology, biogeochemistry, and climate research in the boreal landscape 10.1002/wrcr.20520 Data Management & Analytics Natural Water Bodies No abstract available 319923
publications-1022 PEER_REVIEWED_ARTICLE 2015 J. Christos Vassilicos Dissipation in Turbulent Flows 10.1146/annurev-fluid-010814-014637 Simulation & Modeling Natural Water Bodies This article reviews evidence concerning the cornerstone dissipation scaling of turbulence theory: [Formula: see text], with CÏ”=const., Ï” the dissipation rate of turbulent kinetic energy [Formula: see text], and [Formula: see text] an integral length scale characterizing the energy-containing turbulent eddies. This scaling is intimately linked to the Richardson-Kolmogorov equilibrium cascade. Accumulating evidence shows that a significant nonequilibrium region exists in various turbulent flows in which the energy spectrum has Kolmogorov's −5/3 wave-number scaling over a wide wave-number range, yet Cϔ∌RemI/RenL, with m≈1≈n, ReI a global/inlet Reynolds number, and ReL a local turbulence Reynolds number. 320560
publications-1023 PEER_REVIEWED_ARTICLE 2015 Susumu Goto , J.C. Vassilicos Energy dissipation and flux laws for unsteady turbulence 10.1016/j.physleta.2015.02.025 Simulation & Modeling River Basins No abstract available 320560
publications-1024 PEER_REVIEWED_ARTICLE 2015 J. C. Vassilicos , J.-P. Laval , J.-M. Foucaut , M. Stanislas The streamwise turbulence intensity in the intermediate layer of turbulent pipe flow 10.1017/jfm.2015.241 Uncategorized River Basins The spectral model of Perryet al. (J. Fluid Mech., vol. 165, 1986, pp. 163–199) predicts that the integral length scale varies very slowly with distance to the wall in the intermediate layer. The only way for the integral length scale’s variation to be more realistic while keeping with the Townsend–Perry attached eddy spectrum is to add a new wavenumber range to the model at wavenumbers smaller than that spectrum. This necessary addition can also account for the high-Reynolds-number outer peak of the turbulent kinetic energy in the intermediate layer. An analytic expression is obtained for this outer peak in agreement with extremely high-Reynolds-number data by Hultmarket al. (Phys. Rev. Lett., vol. 108, 2012, 094501;J. Fluid Mech., vol. 728, 2013, pp. 376–395). Townsend’s (The Structure of Turbulent Shear Flows, 1976, Cambridge University Press) production–dissipation balance and the finding of Dallaset al. (Phys. Rev. E, vol. 80, 2009, 046306) that, in the intermediate layer, the eddy turnover time scales with skin friction velocity and distance to the wall implies that the logarithmic derivative of the mean flow has an outer peak at the same location as the turbulent kinetic energy. This is seen in the data of Hultmarket al. (Phys. Rev. Lett., vol. 108, 2012, 094501;J. Fluid Mech., vol. 728, 2013, pp. 376–395). The same approach also predicts that the logarithmic derivative of the mean flow has a logarithmic decay at distances to the wall larger than the position of the outer peak. This qualitative prediction is also supported by the aforementioned data. 320560
publications-1025 PEER_REVIEWED_ARTICLE 2015 T. Dairay , M. Obligado , J. C. Vassilicos Non-equilibrium scaling laws in axisymmetric turbulent wakes 10.1017/jfm.2015.493 Uncategorized Natural Water Bodies We present a combined direct numerical simulation and hot-wire anemometry study of an axisymmetric turbulent wake. The data lead to a revised theory of axisymmetric turbulent wakes which relies on the mean streamwise momentum and turbulent kinetic energy equations, self-similarity of the mean flow, turbulent kinetic energy, Reynolds shear stress and turbulent dissipation profiles, non-equilibrium dissipation scalings and an assumption of constant anisotropy. This theory is supported by the present data up to a distance of 100 times the wake generator’s size, which is as far as these data extend. 320560
publications-1026 PEER_REVIEWED_ARTICLE 2015 S. Laizet , J. Nedić , J. C. Vassilicos The spatial origin of −5/3 spectra in grid-generated turbulence 10.1063/1.4923042 Simulation & Modeling River Basins A combined wind tunnel and computational study of grid-generated turbulence along the centreline shows that the close to −5/3 power law signature of energy spectra in the frequency domain originates relatively close to the grid not only where the velocity derivative statistics become quite suddenly isotropic but also where the turbulent fluctuating velocities are very intermittent and non-Gaussian. As the inlet flow velocity increases, these power laws are increasingly well defined and increasingly close to −5/3 over an increasing range of frequencies. However, this range continuously decreases with streamwise distance from the grid even though the local Reynolds number first increases and then decreases along the same streamwise extent. The intermittency at the point of origin of the close to −5/3 power spectra consists of alternations between intense vortex tube clusters with shallow broad-band spectra and quiescent regions where the velocity fluctuations are smooth with steep energy spectra. 320560
publications-1027 PEER_REVIEWED_ARTICLE 2015 J. Nedić , J. C. Vassilicos Vortex Shedding and Aerodynamic Performance of Airfoil with Multiscale Trailing-Edge Modifications 10.2514/1.j053834 Uncategorized River Basins No abstract available 320560
publications-1028 PEER_REVIEWED_ARTICLE 2015 Sylvain Laizet , Jovan Nedić , Christos Vassilicos Influence of the spatial resolution on fine-scale features in DNS of turbulence generated by a single square grid 10.1080/10618562.2015.1058371 Uncategorized Natural Water Bodies No abstract available 320560
publications-1029 PEER_REVIEWED_ARTICLE 2017 S. BaƟbuğ , G. Papadakis , J. C. Vassilicos DNS investigation of the dynamical behaviour of trailing vortices in unbaffled stirred vessels at transitional Reynolds numbers 10.1063/1.4983494 Uncategorized River Basins Flow in an unbaffled stirred vessel agitated by a four-bladed radial impeller is investigated by using direct numerical simulations at Re = 320 and 1600. We observe fluctuations in the power consumption with a peak frequency at ca. three times the impeller rotational speed for both Reynolds numbers. It is discovered that these fluctuations are associated with a periodic event in the wake of the blades, which involves alternating growth and decay of the upper and lower cores of the trailing vortex pair as well as up-and-down swinging motion of the radial jet. Moreover, the phase relation between the wakes of the different blades is examined in detail. Further studies using fractal-shaped blades show that the exact blade shape does not have a strong influence on this phenomenon. However, the wake interaction between the blades, hence the number of blades, has a direct influence on the unsteadiness of trailing vortices. 320560
publications-1030 PEER_REVIEWED_ARTICLE 2017 Carlos Diaz-Daniel , Sylvain Laizet , J. Christos Vassilicos Wall shear stress fluctuations: Mixed scaling and their effects on velocity fluctuations in a turbulent boundary layer 10.1063/1.4984002 Uncategorized River Basins The present work investigates numerically the statistics of the wall shear stress fluctuations in a turbulent boundary layer (TBL) and their relation to the velocity fluctuations outside of the near-wall region. The flow data are obtained from a Direct Numerical Simulation (DNS) of a zero pressure-gradient TBL using the high-order flow solver Incompact3D [S. Laizet and E. Lamballais, “High-order compact schemes for incompressible flows: A simple and efficient method with quasi-spectral accuracy,” J. Comput. Phys. 228(16), 5989 (2009)]. The maximum Reynolds number of the simulation is Re𝜃≈2000, based on the free-stream velocity and the momentum thickness of the boundary layer. The simulation data suggest that the root-mean-squared fluctuations of the streamwise and spanwise wall shear-stress components τx and τz follow a logarithmic dependence on the Reynolds number, consistent with the empirical correlation of ÖrlĂŒ and Schlatter [R. ÖrlĂŒ and P. Schlatter, “On the fluctuating wall-shear stress in zero pressure-gradient turbulent boundary layer flows,” Phys. Fluids 23, 021704 (2011)]. These functional dependencies can be used to estimate the Reynolds number dependence of the wall turbulence dissipation rate in good agreement with reference DNS data. Our results suggest that the rare negative events of τx can be associated with the extreme values of τz and are related to the presence of coherent structures in the buffer layer, mainly quasi-streamwise vortices. We also develop a theoretical model, based on a generalisation of the Townsend-Perry hypothesis of wall-attached eddies, to link the statistical moments of the filtered wall shear stress fluctuations and the second order structure function of fluctuating velocities at a distance y from the wall. This model suggests that the wall shear stress fluctuations may induce a higher slope in the turbulence energy spectra of streamwise velocities than the one predicted by the Townsend-Perry attached-eddy model. 320560