1,721,212 research outputs found
Dynamics of Nanodroplets on Vibrating Surfaces
No full textThis data folder contains the output data from all molecular dynamics simulations carried out in this paper: Pillai, R, Borg, M & Reese, J 2018, 'Dynamics of nanodroplets on vibrating surfaces' Langmuir. DOI: 10.1021/acs.langmuir.8b02066 .Pillai, Rohit; Borg, Matthew; Reese, Jason. (2018). Dynamics of Nanodroplets on Vibrating Surfaces, [dataset]. University of Edinburgh. School of Engineering. Institute of Multiscale Thermofluids. https://doi.org/10.7488/ds/2432
Mechanical stability of surface nanobubbles
No full textThis data folder contains example 2D and 3D cases for the Molecular Dynamics (MD) simulations, including data from post-processing for the results plotted in the paper: Dockar et al. "Mechanical stability of surface nanobubbles” (in press). MD simulatons were run with LAMMPS version 30 July 2016 (https://lammps.sandia.gov). Each folder starting with the word 'Figure' is linked with the actual Figure in the journal paper, and contains the data used to plot each figure.Dockar, Duncan; Borg, Matthew; Reese, Jason. (2018). Mechanical stability of surface nanobubbles, [dataset]. University of Edinburgh. School of Engineering. Institute of Multiscale Thermofluids. https://doi.org/10.7488/ds/2471
Multiscale simulation of dynamic wetting
No full textThis data set contains the output data from all molecular dynamics and multiscale simulations carried out in the paper entitled: "Multiscale simulation of dynamic wetting" submitted to the International Journal of Heat and Mass Transfer. All data is organised according to the Figure numbers in this paper.Zhang, Jun; Borg, Matthew; Reese, Jason. (2017). Multiscale simulation of dynamic wetting, [dataset]. The University of Edinburgh. School of Engineering. Institute of Multiscale Thermofluids. http://dx.doi.org/10.7488/ds/2077
Droplet Coalescence is Initiated by Thermal Motion
No full textThis data folder contains LAMMPS input files for molecular dynamics (MD) simulations and post-processing codes used in the study: Perumanath et al. https://journals.aps.org/prl/accepted/f6070Y62F8b1396f66d06f366e35c46518e21059e .Perumanath, Sreehari; Borg, Matthew; Chubynsky, Mykyta; Sprittles, James; Reese, Jason. (2019). Droplet Coalescence is Initiated by Thermal Motion, [dataset]. University of Edinburgh. School of Engineering. Institute of Multiscale Thermofluids. https://doi.org/10.7488/ds/2488
Flow enhancement in nanotubes of different materials and lengths
Full text linkThe high water flow rates observed in carbon nanotubes (CNTs) have previously been attributed to the unfavorable energetic interaction between the liquid and the graphitic walls of the CNTs. This paper reports molecular dynamics simulations of water flow in carbon, boron nitride, and silicon carbide nanotubes that show the effect of the solid-liquid interactions on the fluid flow. Alongside an analytical model, these results show that the flow enhancement depends on the tube's geometric characteristics and the solid-liquid interactions. (C) 2014 AIP Publishing LLC.</p
Rarefied gas effects on the aerodynamics of high area-to-mass ratio spacecraft in orbit
Full text linkThe aerodynamic situation of a satellite-on-a-chip operating in low Earth orbit bears some resemblance to a classical Crookes radiometer. The large area-to-mass ratio characteristic of a SpaceChip means that very small surface-dependent forces produce non-negligible accelerations that can significantly alter its orbit. When the temperature of a SpaceChip changes, the drag force can be changed: if the temperature increases, the drag increases (and vice versa). Analytical expressions available in the literature that describe the change in drag coefficient with orbit altitude and SpaceChip temperature compare well with our direct simulation Monte Carlo results presented here. It is demonstrated that modifying the temperature of a SpaceChip could be used for relative orbit control of individual SpaceChips in a swarm, with a maximum change in position per orbit of 50 m being achievable at 600 km altitude
Acoustothermal atomization of water nanofilms
No full textThis data folder contains the output data from all molecular dynamics simulations carried out in this paper.We report nonequilibrium molecular simulations of the vibration-induced heating of nanoscale-thick water layers on a metal substrate. In addition to experimentally confirmed acoustothermal evaporation, we observe hitherto unmapped nucleate and film boiling regimes, accompanied by the generation of unprecedented heat fluxes [∼O(109) W/m2]. We develop a universal scaling parameter to classify the heat-transfer regimes and to predict the thickness of the residual nonevaporating liquid layer. The results find broad application to systems involving drying, coatings, and sprays.Pillai, Rohit; Borg, Matthew; Reese, Jason. (2018). Acoustothermal atomization of water nanofilms, [dataset]. University of Edinburgh. School of Engineering. Institute of Multiscale Thermofluids. http://dx.doi.org/10.7488/ds/2415
FDBB: Fluid dynamics building blocks
No full textHigh-performance computing platforms are becoming more and more heterogeneous, which makes it very difficult for researchers and scientific software developers to keep up with the rapid changes on the hardware market. In this paper, the open-source project FDBB (Fluid Dynamics Building Blocks) is presented, which eases the development of fluid dynamics applications for heterogeneous systems. It consists of a low-level API that provides a unified interface to many different linear algebra back-ends and a lightweight and extendible high-level expression template library, which provides largely customizable fluid dynamics building blocks, like transformations between primary and secondary variables as well as expressions for Riemann invariants, equations of state, inviscid fluxes and their flux-Jacobians. The performance of the developed approach is assessed both for synthetic micro-benchmarks and within mini-applications.Accepted Author ManuscriptNumerical Analysi
Investigation of the gap vortex street in densely packed tube arrays in axial flow using CFD and experiments
No full textAxial flow in tube bundles with small pitch-to-diameter ratio, a geometry encountered in nuclear reactor cores and heat exchangers, often displays periodic fluctuations. A significant velocity discrepancy between the inter-cylinder gap and subchannel center originates from the difference in through-flow area, feeding an instability. As it is associated with velocity-shear, it is similar to the Kelvin-Helmholtz type and the term 'gap instability' is adopted. A vortex street arises and structural vibration of the cylinders might develop due to the fluctuating pressure. Numerical simulations of this phenomenon were performed. The computational domain was constructed to match the most important geometrical features of an experimental setup. The bundle consists of 7 steel tubes in triangular array, placed in a hexagonal conduit. A flexible segment made of silicone is embedded in the central tube, with both extremes clamped to the steel parts of the cylinder. In the experiment, data of the fluctuating velocity was gathered using laser Doppler anemometry measurements. As first step, a completely rigid structure was considered. Unsteady Reynolds-averaged Navier-Stokes (URANS) simulations were used to test if this particular geometry also triggers the gap vortex street, which was the case. The phenomenon clearly appears as oscillations of the velocity components. Subsequently, fluid-structure interaction (FSI) simulations, taking into account the flexible part, allowed to assess the effect of the fluctuating flow field on the structure. A comparison between one-way and two-way coupled simulations was made.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.RST/Reactor Physics and Nuclear Material
Taylor least squares reconstruction technique for material point methods
No full textThe material point method (MPM) is an effective computational tool for simulating problems involving large deformations. However, its direct mapping of the material-point data to the background grid frequently leads to severe inaccuracies. The standard function reconstruction techniques can considerably decrease these errors, but do not always guarantee the conservation of the total mass and linear momentum as the MPM algorithm does. In this paper, we introduce a novel technique, called Taylor Least Squares (TLS), which combines the Least Squares approximation with Taylor basis functions to reconstruct functions from scattered data. Within each element, the TLS technique approximates quantities of interest, such as stress and density, and when used with a suitable quadrature rule, it conserves the total mass and linear momentum after mapping the material-point information to the grid. The numerical and physical properties of the reconstruction technique are first illustrated on one- and two-dimensional functions. Then the TLS technique is tested as part of MPM, Dual Domain Material Point Method (DDMPM), and B-spline MPM (BSMPM) on a one-dimensional problem experiencing small and large deformations. The obtained results show that applying the TLS approximation significantly improves the accuracy of the considered versions of the material point method, while preserving the physical properties of the standard MPM.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Numerical Analysi
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