Computational Fluid Dynamics (CFD)
Behnam Dilmaghani Hassanlouei; Nader Pourmahmoud; Pierre Sullivan
Abstract
In this article, an extracorporeal membrane oxygenator (ECMO) is simulated in 2D geometry using computational fluid dynamics (CFD). Momentum and mass transport equations were solved for the laminar flow regime (30 < Re < 130 for the blood channel) using the finite element method. In this study, ...
Read More
In this article, an extracorporeal membrane oxygenator (ECMO) is simulated in 2D geometry using computational fluid dynamics (CFD). Momentum and mass transport equations were solved for the laminar flow regime (30 < Re < 130 for the blood channel) using the finite element method. In this study, the software COMSOL was used as the solver. To this end, the main problem of ECMO devices is the pressure drop and the risk of thrombus formation due to blood stagnation, so to solve this problem, the oxygen transfer rate to blood should be increased. Therefore, to optimize the oxygen transfer rate of blood, three basic parameters were examined: blood flow velocity, oxygen velocity, and membrane thickness. Blood flow was considered at five different velocities (0.2, 0.4, 0.5, 0.6, and 0.8 mm/s). Results showed that increased blood flow velocity adversely affected oxygen permeability, increasing oxygen permeability from about 60% at 0.2 mm/s to about 24% at 0.9 mm/s. In addition, five different membrane thicknesses (0.04, 0.06, 0.08, 0.2, and 0.3 mm) were investigated, and, as expected, better oxygen exchange occurred as the membrane thickness decreased. We also found that the diffusion rate is about 40% for the 0.4 mm/s thin films and about 25% for the same inlet velocity and larger film thickness. Furthermore, the oxygen diffusivity increases from 28% to 38% as the oxygen gas velocity increases. However, oxygen velocities above 0.8 mm/s should not be used, as the range of oxygen diffusivity variation decreases with higher oxygen gas velocities.
Computational Fluid Dynamics (CFD)
A. Tamil Chandran; T. Suthakar; K. R. Balasubramanian; S. Rammohan; Jacob Chandapillai
Abstract
Numerical analysis of drag coefficient of three-dimensional bluff bodies such as flat plates, cylinder, triangular prism, semicircular profiles located in the flow path of the pipe was performed. Bluff bodies of various lengths are analysed using a turbulence model. The effect of bluff body thickness ...
Read More
Numerical analysis of drag coefficient of three-dimensional bluff bodies such as flat plates, cylinder, triangular prism, semicircular profiles located in the flow path of the pipe was performed. Bluff bodies of various lengths are analysed using a turbulence model. The effect of bluff body thickness on drag coefficient was analysed. A significant observation of the study is the reduction in drag coefficient with an increase in thickness. Effect of pressure coefficient on drag coefficient was evaluated. The study confirms that frictional coefficient has negligible effect on drag coefficient in the studied Reynolds number range. Change in drag coefficient over a wide range of Reynolds number was studied and is reported. Irrespective of geometry and length, the study indicates that there is a significant difference in drag coefficient between two dimensional and three dimensional simulation studies. It is also concluded that the length of a bluff body in a confined domain has a significant effect on its drag coefficient.
Computational Fluid Dynamics (CFD)
Omid Khayat; Hossein Afarideh
Abstract
One of the challenging problems in the Oil & Gas industry is accurate and reliable multiphase flow rate measurement in a three-phase flow. Application of methods with minimized uncertainty is required in the industry. Previous developed correlations for two-phase flow are complex and not capable ...
Read More
One of the challenging problems in the Oil & Gas industry is accurate and reliable multiphase flow rate measurement in a three-phase flow. Application of methods with minimized uncertainty is required in the industry. Previous developed correlations for two-phase flow are complex and not capable of three-phase flow. Hence phase behavior identification in different conditions to designing and modeling of three-phase flow is important. Numerous laboratory and theoretical studies have been done to describe the Venturi multiphase flow meter in both horizontal and vertical flow. However, it is not possible to select the measurement devices for all similar conditions. In this study a new venturi model was developed that implemented in Simulink/Matlab for predicting mass flow rate of gas, water and oil. This models is simple and semilinear. Several classified configurations of three phase flow were simulated using Computational Fluid Dynamics (CFD) analysis to get hydrodynamics parameters of the flows to use as inputs of the model. The obtained data, used as test and train data in Least squares support vector machine (LSSVM) algorithm. The pressure drop, mass flow rate of gas, oil and water have been calculated with LSSVM method. Two tuning parameters of LSSVM, namely γ and σ^2, obtained as 1150954 and 0.4384, 53.9199 and 0.18163, 8.8714 and 0.14424, and 10039130.2214 and 0.74742 for pressure drop, mass flow rate of oil, gas mass flow rate, water mass flow rate, respectively. Developed models was found to have an average relative error of 5.81%, 6.31% and 2.58% for gas, oil and water respectively.
