Using computational fluid dynamics to evaluate a novel venous cannula (Smart canula ®) for use in cardiopulmonary bypass operating procedures

Perfusion ◽  
2007 ◽  
Vol 22 (4) ◽  
pp. 257-265 ◽  
Author(s):  
D. Jegger ◽  
S. Sundaram ◽  
K. Shah ◽  
I. Mallabiabarrena ◽  
G. Mucciolo ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cardiopulmonary Bypass ◽  
Pressure Gradient ◽  
Surface Area ◽  
Mass Flow ◽  
Stokes Equations ◽  
Venous Drainage ◽  
Dimensional System ◽  
Flow Rates

Peripheral access cardiopulmonary bypass (CPB) is initiated with percutaneous cannulae (CTRL) and venous drainage is often impeded due to smaller vessel and cannula size. A new cannula (Smartcanula ®, SC) was developed which can change shape in situ and, therefore, may improve venous drainage. Its performance was evaluated using a 2-D computational fluid dynamics (CFD) model. The Navier-Stokes equations could be simplified due to the fact that we use a steady state and a 2-dimensional system while the equation of continuity (ρ constant) was also simplified. We compared the results of the SC to the CTRL using CFDRC® (Version 6.6, CFDRC research corporation, Huntsville, USA) at two preloads (300 and 700 Pa). The SC's mass flow rate outperformed the CTRL by 12.1% and 12.2% at a pressures of 300 and 700 Pa, respectively. At 700 Pa, a pressure gradient of 50% was measured for the CTRL and 11% for the SC. The mean velocity at the 700 Pa for the CTRL was 1.0 m.s-1 at exit while the SC showed an exit velocity of 1.3 m.s-1. Shear rates inside the cannulae were similar between the two cannulae. In conclusion, the prototype shows greater mass flow rates compared to the classic cannula; thus, it is more efficient. This is also advocated by a better pressure gradient and higher average velocities. By reducing cannula-tip surface area or increasing hole surface area, greater flow rates are achieved. Perfusion (2007) 22, 257—265.

scholarly journals Experimental and CFD studies on determination of injection and production wells location considering reservoir heterogeneity and capillary number

2019 ◽  
Vol 74 ◽  
pp. 4 ◽  
Author(s):  
Pouyan Ahmadi ◽  
Ehsan Ghandi ◽  
Masoud Riazi ◽  
Mohammad Reza Malayeri
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Gradient ◽  
Capillary Number ◽  
Recovery Factor ◽  
Injection Wells ◽  
Flow Rates ◽  
Reservoir Heterogeneity ◽  
Production Wells ◽  
Gradient Line

The in-depth knowledge of reservoir heterogeneity is imperative for identifying the location of production and injection wells. The present study aimed at experimentally investigating the process of water flooding in the viscous oil-saturated glass micromodels, which contain layers with different permeability where the fractures were placed in different locations. Computational Fluid Dynamics (CFD) simulations of flooding were also conducted to study the impact of different water flow rates and wettability states. The results showed that the fractures, which have a deviation with the trend of maximum pressure gradient line, would widen the water path and vice versa. The performance of injection wells would increase the recovery factor by 18% if these would be located in the zones with high permeability for low flow rates of water. With changes in wettability state from water to oil wet conditions, the oil production will increase by 11%. Computational Fluid Dynamics results also indicated that an increase in the capillary number from 0.8 × 10−6 to 1.6 × 10−5, would cause the recovery factor to decrease as much as 14.34% while further increase from 1.6 × 10−5 to 2.24 × 10−5, the oil production will increase by 9.5%. Comparison between the obtained oil recoveries indicates that the maximum oil recoveries will happen when the injector well is located in the zone where ascending permeability, capillary number greater than 4.81 × 10−6 and also fracture with the most deviation with pressure gradient line (i.e. angular pattern) are gathered in an area between the injection and production wells.

Design and analysis of bubble-injected water ramjets with discrete injection configurations by computational fluid dynamics method

2012 ◽  
Vol 227 (9) ◽  
pp. 1945-1955 ◽  
Author(s):  
Arash Nemati Hayati ◽  
Seyed Mohammad Hashemi ◽  
Mehrzad Shams
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mass Flow ◽  
Operating Conditions ◽  
Flow Rates ◽  
Air Mass ◽  
Mixing Chamber ◽  
Mass Flow Rates ◽  
Dynamics Method ◽  
Water Ramjet

In this study, the performance of a typical bubbly water ramjet was investigated by the application of computational fluid dynamics method at different vessel velocities up to 80 knots for a range of air mass flow rates up to 0.9 kg/s. For this purpose, the validity of presented method was preliminarily examined for a converging–diverging nozzle. Then, a designed ramjet with discrete injection configuration was studied at different operating conditions. It was proved that the injection process significantly increases the amount of generated thrust up to 10 times more than the thrust of a single-phase water ramjet. The results suggest that for optimum operation of the ramjet, specific values should be assigned for both inlet and mixing chamber diameters with respect to outlet diameter. Furthermore, it seems that the modification of mixing chamber profile can effectively improve the performance, as the generated thrust of model with throat-like chamber surpasses that for conventional model up to more than two times. Finally, in order to rectify the contradiction of results obtained in previous literatures on the dependency of thrust on vessel velocity, a meaningful relation was derived between the generated thrust of the ramjet with the advance velocity at different air mass flow rates.

scholarly journals Modelling of Chlorine Contact Tank and the Combined Applications of Linear Model Predictive Control and Computational Fluid Dynamics

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
Abrar Muslim ◽  
Qin Li ◽  
Moses O. Tadé
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Model Predictive Control ◽  
Linear Model ◽  
Predictive Control ◽  
Mass Flow ◽  
Decay Process ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Siso System

A dynamic model is developed to present chlorine decay in chlorine contact tank, and a single-input single-output (SISO) model that presents both chlorine dosing and decay process is developed in Simulink of Matlab software with considerations of the process disturbances of temperature and stagnant flow in the tank. A computational fluid dynamics (CFD) model of chlorine transport and decay in the tank is also developed with the use of mixture multiphase model to present the chlorine mixing and decay models in the tank. To optimally control free chlorine residual (FCR) concentration in the SISO system, a linear model predictive control (LMPC) is designed using the SISO system and LMPC control algorithm. The LMPC control objective is to regulate the optimal mass flow rates of gaseous chlorine to control the chlorine decay process inputs/outputs within the constraints. The results on the LMPC simulation using reference data from a real water plant show that the LMPC can control the FCR concentration in the tank within the constraint by regulating the optimal mass flow rates of gaseous chlorine. Commercial CFD software, FluentTM, has been used in this study to simulate the FCR distribution in the CCT channel based on the LMPC result.

scholarly journals Numerical modelling of twin-screw pumps based on computational fluid dynamics

2016 ◽  
Vol 231 (24) ◽  
pp. 4617-4634 ◽  
Author(s):  
Di Yan ◽  
Ahmed Kovacevic ◽  
Qian Tang ◽  
Sham Rane ◽  
Wenhua Zhang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mass Flow ◽  
Dynamics Simulation ◽  
Piping System ◽  
Computational Domain ◽  
Screw Pump ◽  
Flow Rates ◽  
Shaft Power ◽  
Mass Flow Rates

Increasing demands for high-performance screw pumps in oil and gas as well as other applications require deep understanding of the fluid flow field inside the machine. Important effects on the performance such as dynamic losses, influence of the leakage gaps and presence and extent of cavitation are difficult to observe by experiments. However, it is possible to study such effects using well-validated computational fluid dynamics models. The novel-structured numerical mesh consisting of a single-computational domain for moving screw pump rotors was developed to allow three-dimensional computational fluid dynamics simulation of such machine possible. Based on finite volume method, the instantaneous mass flow rates, rotor torque, local pressure field, velocity field and other performance indicators including the indicated power were predicted. A calculation model for the bearing friction losses was introduced to account for mechanical losses. The geometry of the inlet and outlet passages and piping system are taken into consideration to evaluate their influences on the pressure distribution and shaft power. The paper also shows the influence of rotor clearances on the pump performance. The computational fluid dynamics model was validated by comparing the numerical results with the measured performance obtained in the experimental test rig through the comprehensive experiment performed for a set of discharge pressures and rotational speeds. Validation includes comparison of mass flow rates, shaft power and efficiency under variety of speeds and discharge pressure. It has been found that the predicted results match well with the measurements. The results also showed that the radial clearances have larger influence on the mass flow rate than the interlobe clearance. The correct design of the flow passages within the screw pump plays significant role in minimizing required power consumption. The analysis presented in this paper contributes to better understanding of the working process inside the screw pump and offers a good reference to improve design and optimize such machines in terms of clearance selection, shape of the ports, piping system, etc. In future, this model will be used for analysis of cavitating flows and determining performance of other multiphase screw pumps.

Automatic optimization of a centrifugal pump based on impeller–diffuser interaction

2018 ◽  
Vol 232 (8) ◽  
pp. 1004-1018 ◽  
Author(s):  
KM Guleren
Keyword(s):  
Fluid Dynamics ◽  
Genetic Algorithm ◽  
Computational Fluid Dynamics ◽  
Centrifugal Pump ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Increase ◽  
Flow Rates ◽  
Automatic Optimization ◽  
Mass Flow Rates

In this study, a centrifugal pump has been optimized using the genetic algorithm coupled with computational fluid dynamics considering the flow physics for various impeller–diffuser configurations. During the automatic optimization process, the population was selected from a pool of pump geometries generated by four design variables; namely the relative diffuser vane angle, number of diffuser vanes, number of impeller blades, and the impeller wrap angle. The genetic algorithm was combined with a flow solver and a computer aided design software which was used also to create the mesh for the generated geometry. Two objective functions were adopted for the optimization: maximum pressure increase and minimum relative flow angle, which is an indication of reverse flow in the impeller. The iteration history of the optimization for the design (2.4 kg/s) and off-design (3.6 kg/s) flow rate showed that the optimization has been converged to an impeller–diffuser configuration within approximately 250 computational fluid dynamics analyses. Three geometries from each optimization with the highest pressure increase were studied for various mass flow rates and the results were compared with those of the original pump. The results show that the first optimization indicates a significant improvement of pressure increase at design flow rate (15.5%) but decrease at larger flow rates. The second optimization which was required after the results of the first optimization enhanced the head for the entire mass flow rates with an average increase of 25.74%.

Sailing Yacht Rig Improvements Through Viscous Computational Fluid Dynamics

2005 ◽  
Author(s):  
Vincent G. Chapin ◽  
Romaric Neyhousser ◽  
Stephane Jamme ◽  
Guillaume Dulliand ◽  
Patrick Chassaing
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
High Speed ◽  
Stokes Equations ◽  
Wind Tunnel Test ◽  
Physical Modelling ◽  
Optimized Design ◽  
Linear Interaction ◽  
Sailing Yacht

In this paper we propose a rational viscous Computational Fluid Dynamics (CFD) methodology applied to sailing yacht rig aerodynamic design and analysis. After an outlook of present challenges in high speed sailing, we emphasized the necessity of innovation and CFD to conceive, validate and optimize new aero-hydrodynamic concepts. Then, we present our CFD methodology through CAD, mesh generation, numerical and physical modelling choices, and their validation on typical rig configurations through wind-tunnel test comparisons. The methodology defined, we illustrate the relevance and wide potential of advanced numerical tools to investigate sailing yacht rig design questions like the relation between sail camber, propulsive force and aerodynamic finesse, and like the mast-mainsail non linear interaction. Through these examples, it is shown how sailing yacht rig improvements may be drawn by using viscous CFD based on Reynolds Averaged Navier-Stokes equations (RANS). Then the extensive use of viscous CFD, rather than wind-tunnel tests on scale models, for the evaluation or ranking of improved designs with increased time savings. Viscous CFD methodology is used on a preliminary study of the complex and largely unknown Yves Parlier Hydraplaneur double rig. We show how it is possible to increase our understanding of his flow physics with strong sail interactions, and we hope this methodology will open new roads toward optimized design. Throughout the paper, the necessary comparison between CFD and wind-tunnel test will be presented to focus on limitations and drawbacks of viscous CFD tools, and to address future improvements.

The Application of Non-Axisymmetric Endwall Contouring in a Single Stage, Rotating Turbine

2009 ◽  
Author(s):  
Glen Snedden ◽  
Dwain Dunn ◽  
Grant Ingram ◽  
David Gregory-Smith
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Gradient ◽  
Full Scale ◽  
Secondary Flows ◽  
Tip Clearance ◽  
Detailed Understanding ◽  
Low Speed ◽  
Endwall Contouring ◽  
Probe Measurements

As turbine manufacturers strive to develop machines that are more efficient, one area of focus has been the control of secondary flows. To a large extent these methods have been developed through the use of computational fluid dynamics and detailed measurements in linear and annular cascades and proven in full scale engine tests. This study utilises 5-hole probe measurements in a low speed, model turbine in conjunction with computational fluid dynamics to gain a more detailed understanding of the influence of a generic endwall design on the structure of secondary flows within the rotor. This work is aimed at understanding the influence of such endwalls on the structure of secondary flows in the presence of inlet skew, unsteadiness and rotational forces. Results indicate a 0.4% improvement in rotor efficiency as a result of the application of the generic non-axisymmetric endwall contouring. CFD results indicate a clear weakening of the cross passage pressure gradient, but there are also indications that custom endwalls could further improve the gains. Evidence of the influence of endwall contouring on tip clearance flows is also presented.

Optimization of Biomimetic Propulsive Kinematics of a Flexible Foil Using Integrated Computational Fluid Dynamics–Computational Structural Dynamics Simulations

2018 ◽  
Vol 141 (6) ◽  
Author(s):  
Jiho You ◽  
Jinmo Lee ◽  
Seungpyo Hong ◽  
Donghyun You
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Young’S Modulus ◽  
Phase Angle ◽  
Structural Dynamics ◽  
Stokes Equations ◽  
Young's Modulus ◽  
Immersed Boundary ◽  
Computational Structural Dynamics ◽  
Dynamics Simulations

A computational methodology, which combines a computational fluid dynamics (CFD) technique and a computational structural dynamics (CSD) technique, is employed to design a deformable foil whose kinematics is inspired by the propulsive motion of the fin or the tail of a fish or a cetacean. The unsteady incompressible Navier–Stokes equations are solved using a second-order accurate finite difference method and an immersed-boundary method to effectively impose boundary conditions on complex moving boundaries. A finite element-based structural dynamics solver is employed to compute the deformation of the foil due to interaction with fluid. The integrated CFD–CSD simulation capability is coupled with a surrogate management framework (SMF) for nongradient-based multivariable optimization in order to optimize flapping kinematics and flexibility of the foil. The flapping kinematics is manipulated for a rigid nondeforming foil through the pitching amplitude and the phase angle between heaving and pitching motions. The flexibility is additionally controlled for a flexible deforming foil through the selection of material with a range of Young's modulus. A parametric analysis with respect to pitching amplitude, phase angle, and Young's modulus on propulsion efficiency is presented at Reynolds number of 1100 for the NACA 0012 airfoil.

Development of SIMPLE-Like Algorithms for Incompressible Navier-Stokes Equations in Liquid Processing of Materials

2012 ◽  
Vol 184-185 ◽  
pp. 944-948 ◽  
Author(s):  
Hai Jun Gong ◽  
Yang Liu ◽  
Xue Yi Fan ◽  
Da Ming Xu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Stokes Equations ◽  
Simple Algorithm ◽  
Navier Stokes ◽  
Incompressible Fluid Flow ◽  
Numerical Accuracy ◽  
Simple Scheme ◽  
Navier Stokes Equations ◽  
Computational Fluid Dynamics Cfd

For a clear and comprehensive opinion on segregated SIMPLE algorithm in the area of computational fluid dynamics (CFD) during liquid processing of materials, the most significant developments on the SIMPLE algorithm and its variants are briefly reviewed. Subsequently, some important advances during last 30 years serving as increasing numerical accuracy, enhancing robustness and improving efficiency for Navier–Stokes (N-S) equations of incompressible fluid flow are summarized. And then a so-called Direct-SIMPLE scheme proposed by the authors of present paper introduced, which is different from SIMPLE-like schemes, no iterative computations are needed to achieve the final pressure and velocity corrections. Based on the facts cited in present paper, it conclude that the SIMPLE algorithm and its variants will continue to evolve aimed at convergence and accuracy of solution by improving and combining various methods with different grid techniques, and all the algorithms mentioned above will enjoy widespread use in the future.

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