Papers by Mohammed G Al-Azawy
International Journal of Heat and Technology, Feb 28, 2022
In this paper, a micro pin fin heat sink is numerically investigated with four fins geometries (c... more In this paper, a micro pin fin heat sink is numerically investigated with four fins geometries (circular, elliptical, square, and drop shape) at two types of arrangement styles, inline and staggered arrangement. The hydrodynamic and thermal characteristics of different fin geometries and two arrangement styles have been compared under the exact value of Reynolds number and constant wall temperature thermal boundary conditions. The Reynolds number was sweeping in the range of (400-2800) to ensure the fluid flow velocity impact in the pin fin performance. The results obtained indicate that a longitude pin fin dropped with increasing Reynolds number at a distributed temperature. Also, the circler Pin fin reaches the lowest temperature comparison to the rest of the three-pin fin types. Generally, according to the extracted, Nusselt number for different geometries increased versus increasing the Reynolds number. Observe that the elliptical fin shape yields the highest Nusselt number at all Reynolds numbers. Moreover, the elliptical pin fin ejects the highest heat transfer rate, which indicates the pin fin performance. Furthermore, skin friction has a significant function with variation in Reynolds number.
Evaluation of Turbulence and Non-Newtonian Blood Rheology Models Through An FDA Nozzle
2021 International Conference on Advance of Sustainable Engineering and its Application (ICASEA), 2021
International Journal of Heat and Technology, 2021
The fluidized bed and the fluidization process and characteristics were studied in this paper num... more The fluidized bed and the fluidization process and characteristics were studied in this paper numerically using Computational Fluid Dynamics (CFD) Ansys Fluent 15.0. Constant temperature was applied to both sides of the two-dimensional fluidized bed geometry. The superficial velocity of the working fluid ranged amid (0.08 – 0.5 m/s) and the initial height of the solid particles changed amid (0.05, 0.1, 0.2 m). Aluminum particles and water was used as working materials within the fluidized bed. The model used for the investigations was validated using Ngoh and Lim research results. The results showed that the fluidization head increases as the water inlet superficial velocity increases. As well as when the water inlet superficial velocity increases, the average solid phase temperature increases.
Wasit Journal of Engineering Sciences, 2021
This article describes the numerical investigation of blood rheology within an artery that includ... more This article describes the numerical investigation of blood rheology within an artery that includes two narrowing areas via Computational Fluid Dynamics (CFD) to offer guidance to the community, especially surgeons, and help them to avoid the risk of stenosis. Elliptic blending Reynolds stress model and two models of viscosity have been used in this investigation utilizing STAR-CCM+ 2021.2.1. The test model includes two elliptical stenosis with a 2mm distance between them, and the area of stenosis is 75%. Results of normalized axial velocity, turbulent kinetic energy (TKE) and turbulent viscosity ratio (TVR) were evaluated before, through and after the stenosis in order to predict and avoid the real problems that occur from changing the area of the artery. Furthermore, Fractional flow reserve (FFR) was employed to assess the level of risk of stenosis through the artery, which depends on pressure measurements. Corresponding to the author's observation, it was found that the recir...
International Journal of Heat and Technology, 2021
Cardiovascular diseases were the main cause for loosing lives in the last decades due to the rest... more Cardiovascular diseases were the main cause for loosing lives in the last decades due to the restricted blood flow states in the blood vessels areas. Numerical investigations have been conducted as the aim of this work to examine the blood flow, and wall shear stresses adjacent to the mono stenosis up to different degrees involved in the main, side and distal main branches as well as observe the pulsatile flow of blood in the left coronary artery through various percentage of stenosis. Both the Carreau non-Newtonian rheological model and the Newtonian model were utilized to model the blood fluid and wall shear stresses of left coronary artery, in a row, all the calculated data were validated with the previously published papers. It was found that the blood flow inside areas of the artery lie within the range of non-Newtonian rheological effects can be present, verifying the need to treat blood as non-Newtonian fluid; especially, with the case of 90% blockage.
Proceedings of the 9th International Joint Conference on Biomedical Engineering Systems and Technologies, 2016
A comprehensive Computational Fluid Dynamics (CFD) simulation of transient, non-Newtonian, and tu... more A comprehensive Computational Fluid Dynamics (CFD) simulation of transient, non-Newtonian, and turbulent blood flow through a positive displacement pump, left ventricular assist device (LVAD), is executed. Non-Newtonian blood flow is conducted to investigate the flow through a pulsatile pump LVAD by using common blood viscosity model: Carreau. The numerical results of non-Newtonian fluid with a turbulence model, Elliptic Blending Reynolds Stress Model (EB-RSM) are presented. The computational domain that has been selected is a pulsatile pump, which includes valves and a moving pusher plate. An overset mesh zero gap technique was employed to capture the cyclic motion of pusher plate and valves rotation to mimic the scenario of a natural heart. The use of this technique to rotate the valves and ensure full valve closure presented a good agreement results with the experimental data.
Determination of Point of Zero Charge (PZC) of Concrete Particles Adsorbents
IOP Conference Series: Materials Science and Engineering, 2021
In the present study, the pH point of zero charge (pHpzc) was determined for concrete particles a... more In the present study, the pH point of zero charge (pHpzc) was determined for concrete particles adsorbent. The Mass Titration (MT) Method was adopted, and the adsorbent was used to remove the fluoride from water. The pH of point zero charge of concrete adsorbent was found to be 12. The data of pHpzc of the adsorbents give information about the attraction and repulsion between adsorbents and adsorbates. The mass titration technique was found to be an easy way to determine the pHpzc of the studied material.
Concrete particles for fluoride removal using continued fixed-bed and fluidized-bed systems
IOP Conference Series: Materials Science and Engineering, 2021
In the present study, fluoride ions removal from aqueous solution was studied by adsorption using... more In the present study, fluoride ions removal from aqueous solution was studied by adsorption using a new low cost adsorbent which is concrete particles in continuous systems. The continuous systems included fixed and fluidized bed reactor. several operating conditions were used for both of fixed and fluidized column; flow rate (6,9 and 12) l/h, bed depth (6,12,20) cm inlet fluoride concentration (10,15 and 20) mg/l. Thomas and Yoon–Nelson models were used in this study using the data of breakthrough curves for the optimal conditions (bed height of 20 cm, influent flow rate of 6 l/h and inlet fluoride concentration of 10 mg/l). Adsorption capacity of the concrete particles was found to be 0.818 mg/g and 0.73 mg/g for fluidized and fixed bed respectively for the optimum conditions. The adsorption test using concrete particles adsorbent revealed the good performance of removing fluoride from aqueous solution.
CFD Letters, 2020
In order to imitate the atherosclerosis artery disease and determine the key issues, Computationa... more In order to imitate the atherosclerosis artery disease and determine the key issues, Computational Fluid Dynamics (CFD) is able to play a leading rule in the analysis of flow physics within the clogged arteries, in particular the stenosis artery. The problem of blood flow blockage through the blood vessel has been investigated numerically within a stenosis artery. In this work, a CFD technique was employed to solve the three-dimensional, steady, laminar and non-Newtonian Carreau model blood flow through a stenosis artery using Star-CCM+ software. The shape of stenosis that has been selected is a trapezoidal with two cases (70% and 90% blockage). Shear rate, streamlines, vorticity and importance factor are examined to assess the influence of non-Newtonian model through the test section, the Carreau model was compared with Newtonian model. The clinical significance of the shear rate is reported for the examined cases, observing that the levels of non-Newtonian model are predicted to b...
Investigating the Use of Turbulence Models for Flow Investigations in a Positive Displacement Ventricular Assist Device
IFMBE Proceedings, 2015
Computational fluid dynamics (CFD) is applied to study the hemodynamics of flow inside a pulsatil... more Computational fluid dynamics (CFD) is applied to study the hemodynamics of flow inside a pulsatile pump left ventricular assist device (LVAD), in order to evaluate the hemolysis and thrombus formation. The positive displacement or pulsatile pump, which includes valves and a pusher plate (to mimic the natural heart), is the focus of this study. Turbulence is observed to play an important role in the accuracy of predicted levels of shear stress and strain rate, both of which are crucial in assessing the long term feasibility of the device.
Assessment of a transition turbulence model for pulsatile flow inside a heart pump
International Journal for Numerical Methods in Biomedical Engineering, 2016
A detailed computational fluid dynamics (CFD) study of transient, turbulent blood flow through a ... more A detailed computational fluid dynamics (CFD) study of transient, turbulent blood flow through a positive displacement left ventricular assist device is performed. Two common models for non-Newtonian blood flow are compared to the Newtonian model to investigate their impact on predicted levels of shear rate and wall shear stress. Given that both parameters are directly relevant to the evaluation of risk from thrombus and haemolysis, there is a need to assess the sensitivity to modelling non-Newtonian flow effects within a pulsatile turbulent flow, in order to identify levels of uncertainly in CFD. To capture the effects of turbulence, the elliptic blending Reynolds stress model is used in the present study, on account of superior performance of second moment closure schemes previously identified by the present authors. The CFD configuration includes two cyclically rotating valves and a moving pusher plate to periodically vary the chamber volume. An overset mesh algorithm is used for each instance of mesh motion, and a zero gap technique was employed to ensure full valve closure. The left ventricular assist device was operated at a pumping rate of 86 BPM (beats per minute) and a systolic duration of 40% of the pumping cycle, in line with existing experimental data to which comparisons are made. The sensitivity of the variable viscosity models is investigated in terms of mean flow field, levels of turbulence and global shear rate, and a non-dimensional index is used to directly evaluate the impact of non-Newtonian effects. The clinical relevance of the results is reported along with a discussion of modelling uncertainties, observing that the turbulent kinetic energy is generally predicted to be higher in non-Newtonian flow than that observed in Newtonian flow.
Erratum: Investigating the Use of Turbulence Models for Flow Investigations in a Positive Displacement Ventricular Assist Device
IFMBE Proceedings, 2015
Assessment of turbulence models for pulsatile flow inside a heart pump
Computer Methods in Biomechanics and Biomedical Engineering, 2015
Computational fluid dynamics (CFD) is applied to study the unsteady flow inside a pulsatile pump ... more Computational fluid dynamics (CFD) is applied to study the unsteady flow inside a pulsatile pump left ventricular assist device, in order to assess the sensitivity to a range of commonly used turbulence models. Levels of strain and wall shear stress are directly relevant to the evaluation of risk from haemolysis and thrombosis, and thus understanding the sensitivity to these turbulence models is important in the assessment of uncertainty in CFD predictions. The study focuses on a positive displacement or pulsatile pump, and the CFD model includes valves and moving pusher plate. An unstructured dynamic layering method was employed to capture this cyclic motion, and valves were simulated in their fully open position to mimic the natural scenario, with in/outflow triggered at control planes away from the valves. Six turbulence models have been used, comprising three relevant to the low Reynolds number nature of this flow and three more intended to investigate different transport effects. In the first group, we consider the shear stress transport (SST) [Formula: see text] model in both its standard and transition-sensitive forms, and the 'laminar' model in which no turbulence model is used. In the second group, we compare the one equation Spalart-Almaras model, the standard two equation [Formula: see text] and the full Reynolds stress model (RSM). Following evaluation of spatial and temporal resolution requirements, results are compared with available experimental data. The model was operated at a systolic duration of 40% of the pumping cycle and a pumping rate of 86 BPM (beats per minute). Contrary to reasonable preconception, the 'transition' model, calibrated to incorporate additional physical modelling specifically for these flow conditions, was not noticeably superior to the standard form of the model. Indeed, observations of turbulent viscosity ratio reveal that the transition model initiates a premature increase of turbulence in this flow, when compared with both experimental and higher order numerical results previously reported in the literature. Furthermore, the RSM is indicated to provide the most accurate prediction over much of the flow, due to its ability to more correctly account for three-dimensional effects. Finally, the clinical relevance of the results is reported along with a discussion on the impact of such modelling uncertainties.
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Papers by Mohammed G Al-Azawy