Search results for "computational fluid dynamic"
showing 10 items of 200 documents
Unsteadiness and transition to turbulence in woven spacer filled channels for Membrane Distillation
2017
To characterize the performance of Membrane Distillation (MD) modules, channels filled with woven spacers were investigated by Computational Fluid Dynamics (including Direct Numerical Simulations and the use of the SST k-Ï turbulence model) and by parallel experiments with Thermochromic Liquid Crystals. The cases considered here regard mutually orthogonal filaments with a spacer pitch to channel height ratio P/H=2, two spacer orientations θ with respect to the main flow (0° and 45°), and bulk Reynolds numbers Re from â¼200 to â¼2000, an interval of great interest in practical MD applications. For both values of θ, CFD predicted steady-state flow for Re up to â¼300, and chaotic flow …
Permeability network model for non-crimp fabrics
2006
In this work a global permeability model is developed and applied to a biaxial Non-crimp stitched fabric (NCF). This model focuses on a detailed meso-scale description of the fabric geometry, which takes into account the local permeability distribution in a fabric due to perturbations of the geometry as well as the geometrical features which arise from the stitching process. It is shown in this work that these features significantly affects the global permeability. The influence of the amount and type of perturbation of a fabric is also studied in this work. It is shown that perturbation of the fabric geometry affect the global permeability but not as much as the stitching process. The mode…
Conduit dynamics and post explosion degassing on Stromboli: A combined UV camera and numerical modeling treatment.
2016
Abstract Recent gas flux measurements have shown that Strombolian explosions are often followed by periods of elevated flux, or “gas codas,” with durations of order a minute. Here we present UV camera data from 200 events recorded at Stromboli volcano to constrain the nature of these codas for the first time, providing estimates for combined explosion plus coda SO2 masses of ≈18–225 kg. Numerical simulations of gas slug ascent show that substantial proportions of the initial gas mass can be distributed into a train of “daughter bubbles” released from the base of the slug, which we suggest, generate the codas, on bursting at the surface. This process could also cause transitioning of slugs i…
Experimental and numerical investigation of the leading edge sweep angle effect on the performance of a delta blades hydrokinetic turbine
2020
Abstract In the last decades, an increase of energy consumption has been noted around the world. Hence, the excessive use of fossil fuels can lead to serious environmental concerns. Indeed, the use of renewable energy sources is needed to reduce the greenhouse gas effects and the CO2 emissions in the atmosphere. Small-scale hydropower could be an interesting and renewable alternative solution. The cross-flow turbines present several advantages compared to the axial-flow turbines. Therefore, increasing efforts are taken to enhance the efficiency and extend the applicability of the cross-flow turbines. In this paper, experimental investigation was carried out to evaluate the performance of a …
Numerical prediction of ventilated planing flat plates for the design of Air Cavity Ships
2017
In recent years, a great world issue is the respect for the environment. Each researcher, in his competence field, proposes new technologies and new approaches in order to reduce the environmental impact of a product or of an industrial process. In the naval field, the main way in order to reduce the environmental impact of the ship during the navigation is the reduction of the drag resistance and so the reduction of requested power. There are many ways in order to obtain a reduction of drag. This paper investigates, with a preliminary numerical study by means of Computational Fluid Dynamics (CFD), the Air Cavity Ships technology (ACS). A first part of the paper concerns the study of the ri…
Shear stress alterations in the celiac trunk of patients with a continuous-flow left ventricular assist device as shown by in-silico and in-vitro flo…
2017
Background The use of left ventricular assist devices (LVADs) to treat advanced cardiac heart failure is constantly increasing, although this device leads to high risk for gastrointestinal bleeding. Methods Using in-silico flow analysis, we quantified hemodynamic alterations due to continuous-flow LVAD (HeartWare, Inc., Framingham, MA) in the celiac trunk and major branches of the abdominal aorta, and then explored the relationship between wall shear stress (WSS) and celiac trunk orientation. To assess outflow from the aortic branch, a 3-dimensional-printed patient-specific model of the celiac trunk reconstructed from an LVAD-supported patient was used to estimate echocardiographic outflow …
Design of a reactor operating in supercritical water conditions using CFD simulations. Examples of synthesized nanomaterials
2011
International audience; Direct information about fluids under supercritical water conditions is unfeasible due to the engineering restrictions at high pressure and high temperature. Numerical investigations based on computational fluid dynamics (CFD) calculations are widely used in order to get extensive information on the fluid behavior, particularly to help the design of a new reactor. This paper presents the numerical investigations performed on an original supercritical water device, especially in the level of the reactor. CFD calculations allow to design and optimize the present reactor described in this study. Currently, this process produces some nanometric oxide powders in continuou…
Modeling of Magnetic-Field-Assisted Fluidization: Model Development and CFD Simulation of Magnetically Stabilized Fluidized Beds
2014
Magnetic-field-assisted fluidization is starting to be considered as a viable alternative to standard fluidized beds for those operations (such as particle separations, filtration, adsorption) in which the solid phase can be made of magnetic particles or, alternatively, the fluidizing agent is a ferro-fluid; thus the fluid bed responds to the action of magnetic fields, and stabilized fluidization regimes can be generated. One of the major difficulties to be tackled is the development of a predictive model capable of estimating the stabilized-to-bubbling transition velocity for a given magnetic field or, on the other hand, the magnetic field intensity required to stabilize the bed to a quies…
Geometric Analysis of Type B Aortic Dissections Shows Aortic Remodeling After Intervention Using Multilayer Stents
2020
Recently, multilayer stents for type B aortic dissections (TBAD) have been proposed to decrease false lumen flow, increase and streamline true lumen flow, and retain branch vessel patency. We aimed to provide a protocol with standardized techniques to investigate aortic remodeling of TBAD by multilayer flow modulators (MFM) in static geometric and hemodynamic analyses. Combining existing literature and new insights, a standardized protocol was designed. Using pre- and postoperative CT scans, geometric models were constructed, lumen dimensions were calculated, computational fluid dynamics (CFD) models were composed, and velocity and pressures were calculated. Sixteen TBAD cases treated with …
On the thermal-hydraulic performances of the DEMO divertor cassette body cooling circuit equipped with a liner
2020
Abstract In the framework of the Work Package DIV 1 - “Divertor Cassette Design and Integration” of the EUROfusion action, a research campaign has been jointly carried out by University of Palermo and ENEA to investigate the steady-state thermal-hydraulic performances of the DEMO divertor cassette cooling system. The research activity has been focussed onto the most recent design of the Cassette Body (CB) cooling circuit, consistent with the DEMO baseline 2017 and equipped with a liner, whose main function is to protect the underlying vacuum pump CB opening from plasma radiation. The research campaign has been carried out following a theoretical-computational approach based on the finite vo…