1,721,014 research outputs found
Artificial compressibility based CBS solutions for double diffusive natural convection in cavities
No full textEffectiveness of flow obstructions in enhancing electro-osmotic flow
Full text linkIn this paper the influence of obstructions on micro-channel electroosmotic flow is investigated for the first time. To carry out such a study, regular obstructions are introduced into micro-channels and flow rates are numerically calculated. The effect of channel width on flow rates is analysed on both free and obstructed channels. The solid material considered for channel walls and obstructions is silicon and the electrolyte is de-ionised water. The parameters studied include channel width, obstruction size and effective porosity of the channel. The effective porosity is varied between 0.4 and 0.8 depending on other chosen parameters. The results clearly demonstrate that, under the analysed conditions, introduction of obstructions into channels wider than100 micro meters enhances the flow rate induced by electro-osmosis
Using flow obstructions in electro-osmotic systems for fluid flow enhancement
No full textA numerical investigation of Electro-Osmotic Flow (EOF) in plain channels and channels with obstructions is presented. The aim of the work is to analyse fluid flow enhancement in EO systems due to flow obstructions. The results show that the introduction of flow obstructions allows to increase the range of channel width in which EOF is effective, and to produce higher fluid flow rates than those corresponding to plain channels. The results also show that beyond a channel width of 100μm, EOF driven systems are possible only if flow obstructions are employed
A generalised porous medium approach to study thermo-fluid dynamics in human eyes
Full text linkThe present work describes the application of the generalised porous medium model to study heat and fluid flow in healthy and glaucomatous eyes of different subject specimens, considering the presence of ocular cavities and porous tissues. The 2D computational model, implemented into the open-source software OpenFOAM, has been verified against benchmark data for mixed convection in domains partially filled with a porous medium. The verified model has been employed to simulate the thermo-fluid dynamic phenomena occurring in the anterior section of four patient-specific human eyes, considering the presence of anterior chamber (AC), trabecular meshwork (TM), Schlemm’s canal (SC), and collector channels (CC). The computational domains of the eye are extracted from tomographic images. The dependence of TM porosity and permeability on intraocular pressure (IOP) has been analysed in detail, and the differences between healthy and glaucomatous eye conditions have been highlighted, proving that the different physiological conditions of patients have a significant influence on the thermo-fluid dynamic phenomena. The influence of different eye positions (supine and standing) on thermo-fluid dynamic variables has been also investigated: results are presented in terms of velocity, pressure, temperature, friction coefficient and local Nusselt number. The results clearly indicate that porosity and permeability of TM are two important parameters that affect eye pressure distribution
On some numerical aspects of an active strain model in cardiac mechanics
No full textWe are interested in the development, implementation and testing of an orthotropic model for cardiac contraction based on an active strain decomposition. Our model addresses the coupling of a transversely isotropic mechanical description at the cell level, with an orthotropic constitutive law for incompressible tissue at the macroscopic level. The main differences with the active stress model are addressed in detail, and a finite element discretization using Taylor-Hood and MINI elements is proposed and illustrated with numerical examples.CMC
Coupled models for integrated heart simulations: a numerical study of the fluid dynamics in the left ventricle
No full textWe consider the numerical simulation of integrated heart models for the study of the cardiac functioning with particular emphasis on the coupling of the muscle contraction, the fluid dynamics of the left ventricle, and the interaction with the valves. We address the numerical approximation of the blood flows inside the left ventricle by using the Finite Element method for the spatial approximation of the fluid–structure interaction problem together with the aortic valve and the cardiac muscle, specifically when the contraction of the latter is driven by electromechanical models. We present and discuss numerical results for the fluid dynamics of the left ventricle by analyzing the role of different coupling strategies.CMCSSCI-SB-S
Automated extraction of the femoral anatomical axis for determining the intramedullary rod parameters in total knee arthroplasty
No full textImpact of physiologically inspired boundary conditions on fluid pressure and flow in a computational fluid dynamics model of the cerebrospinal fluid
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