Search results for "Computational fluid dynamic"
showing 10 items of 200 documents
CFD Predictions of Sufficient Suspension Conditions in Solid-Liquid Agitated Tanks
2012
Abstract Most research efforts on mechanically agitated solid-liquid contactors have been devoted to the assessment of the minimum impeller speed for complete off-bottom suspension, N js . Actually, many industrial vessels are operated at impeller speeds slightly lower than N js (Oldshue, 1983; Rieger et al., 1988). This suggests that the sufficient suspension condition, which is quantitatively specified in this paper by introducing a suitably defined quantity N ss , may represent a valid alternative to that of complete suspension. In the present work time-dependent RANS simulations were carried out with the aim of predicting the achievement of sufficient suspension conditions. The Eulerian…
Visualization of Parameter Sensitivity of 2D Time-Dependent Flow
2018
In this paper, we present an approach to analyze 1D parameter spaces of time-dependent flow simulation ensembles. By extending the concept of the finite-time Lyapunov exponent to the ensemble domain, i.e., to the parameter that gives rise to the ensemble, we obtain a tool for quantitative analysis of parameter sensitivity both in space and time. We exemplify our approach using 2D synthetic examples and computational fluid dynamics ensembles.
CFD Assisted Steady-State Modelling of Restrictive Counterbalance Valves
2020
The counterbalance valve is an important component in many hydraulic applications and its behaviour hugely impacts system stability and performance. Despite that, CBVs are rarely modelled accurately due to the effort required to obtain basic model parameters and the complexity involved in identifying expressions for flow forces and friction. This paper presents a CFD assisted approach to steady-state modelling of CBVs. It is applied to a 3-port restrictive commercially available counterbalance valve. The model obtained is based on detailed measurements of the valve geometry, a single data set and CFD modelling and includes flow forces and friction. The CFD assisted model is compared to expe…
Evaluation of the Thermodynamic Performance of the Traditional Passive Systems
2011
The need to reduce urban consumption of energy in the buildings, one of the major energy waster resulting in emission of CO2, is pushing research in the field of building design to the appreciation of passive air-conditioning systems that can be integrated with conventional systems and determine, therefore, the so-called hybrid systems. Historically this passive systems were developed in the Mediterranean and in the Middle East area. Actually the research activity has been focused on this problem, through an approach that involves the application of design strategies and the development of computational tools and control systems. The synergy between current scientific knowledge, advanced ma…
Sedimentation Tanks for Treating Rainwater: CFD Simulations and PIV Experiments
2021
The removal of solids is the most important step when treating rainwater. The article evaluates two designs of sedimentation tanks that can be used for the continuous separation of fine particles from water: OS—standard sedimentation tanks, and OW—swirl sedimentation tanks. The tanks were studied by conducting computational fluid dynamics (CFD) modeling and particle image velocimetry (PIV) experiments. The settling process in sedimentation tank was carried out at varying operating flow rates. A tank with a modified structure was used for the tests, where water was supplied by a nozzle placed at an angle. This solution made it possible to obtain a rotational flow that transported the suspend…
CFD simulation of a membrane distillation module channel
2009
The interest towards the use of membrane distillation (MD) processes for seawater desalination has been rising recently due to the ease of coupling MD with waste and/or solar thermal energy. Notwithstanding the flexibility of the process and its potential for further developments in membrane performances, one of the main drawbacks is the thermal efficiency reduction caused by temperature polarization. Because of such phenomenon, only a small amount of the driving force potentially available for the separation process, i.e. the temperature difference between evaporating and condensing fluids, is actually used for the separation. In order to reduce temperature polarization a study on the effe…
Numerical study of the accuracy of temperature measurement by thermocouples in small-scale reactors
2018
Proper temperature measurement is imperative in any laboratory study if reliable data are to be obtained, particularly in the field of chemical kinetics. In this paper we analyze in silico some typical thermowell configurations used in small-scale reactors by coupling computational fluid dynamics (CFD) with conjugated heat transfer phenomena. This allows us to identify deviations in measurements arising from thermal radiation and self-conductivity in mid and high temperature ranges, in addition to radial temperature gradients. A novel design is proposed and optimized by additional simulation, showing potential for faster and more accurate temperature measurements.
On the Effect of Slotted Blades on Savonius Wind Generator Performances by CFD Analysis
2012
In this paper a new bucket configuration for Savonius wind generator is proposed. With the aim to increase the effect of the overlap ratio RS on the wind turbine performances and to increase the amount of lift force able to produce torque and power, slotted blades are investigated by means of the Computational Fluid Dynamics analysis. The numerical analyses are performed by Comsol Multiphysics® and the results obtained for a Savonius wind turbine with overlap only are compared to numerical and experimental benchmarks. Parametric analyses are performed, for fixed overlap ratio, by varying the slot angle β and the results show that for low angle β the Savonius rotor exploits improved performa…
Laboratori virtual d'ensenyament-aprenentatge: solució numèrica de les equacions de conservació mitjançant volums finits aplicades a superfícies este…
2014
En este treball es presenta el disseny d’un Laboratori virtual d’ensenyament-aprenentatge per a la resolució d’un problema model de Transferència de la Calor en la matèria d’Enginyeria Tèrmica del II curs del Grau d’Enginyer de Tecnologies Industrials de la Universidad Rey Juan Carlos de Madrid. En l’àmbit de la Dinàmica de Fluids Computacional i per mitjà de l’ús del programari de simulació d’Ansys Fluent s’introduïx l’alumne al disseny, modelatge del sistema, resolució, anàlisi i validació del model. El resultat d’esta experiència d’aprenentatge és no sols la mera resolució del problema, inabordable amb mètodes didàctics tradicionals, sinó el desenvolupament de la combinació de destreses,…