Two-Phase Non-Linear Model for the Flow Through Stenosed Blood Vessels

D. S. Sankar,Usik Lee 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.4

Pulsatile flow of a two-phase model for blood flow through arterial stenosis is analyzed through a mathematical analysis. The effects of pulsatility, stenosis, peripheral layer and non-Newtonian behavior of blood, assuming the blood in the core region as a Herschel-Bulkley fluid and the plasma in the peripheral layer as a Newtonian fluid, are discussed. A perturbation method is used to solve the resulting system of non-linear quasi-steady differential equations. The expressions for velocity, wall shear stress, plug core radius, flow rate and resistance to flow are obtained. It is noticed that the plug core radius and resistance to flow increase as the stenosis size increases while all other parameters held constant. The wall shear stress increases with the increase of yield stress while keeping other parameters as invariables. It is observed that the velocity increases with the axial distance in the stenosed region of the tube upto the maximum projection of the stenosis.

A Pilot Study of Open Label Sesame Oil in Hypertensive Diabetics

D. Sankar,M. Ramakrishna Rao,G. Sambandam,K.V. Pugalendi 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.3

The objective of this study was to investigate the effect of sesame oil in hypertensive diabetics medicated withatenolol (.-blocker) and glibenclamide (sulfonylurea). This open label trial with two intervention periods comprised 22 maleand 18 female patients, 4565 years old, with mild to moderate hypertension and diabetes. Sesame oil (Idhayam Gingelly™oil, V.V.V. & Sons, Virudhunagar, Tamilnadu, India) was supplied to the patients, who were instructed to use it in place ofother cooking oils for 45 days. Blood pressure (BP), anthropometric measurements, plasma glucose, glycated hemoglobin(HbA1c), lipid profiles [total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein choles-terol, and triglycerides (TG)], lipid peroxidation [thiobarbituric acid-reactive substances (TBARS)], electrolytes (sodium, potas-sium, and chloride), and enzymic (superoxide dismutase, glutathione peroxidase, and catalase) and nonenzymic (vitamin C,vitamin E, .-carotene, and reduced glutathione) antioxidants were measured at baseline and after 45 days of sesame oil sub-stitution. The same patients were then switched over to other oils like palm or groundnut oils as their regular oils at randomfor another 45 days, and the investigations were carried out again at the end. Systolic and diastolic BP decreased remarkably.When oil substitution was withdrawn, BP values rose again. Body weight, body mass index, girth of waist, girth of hip, andwaist:hip ratio were reduced upon substitution of sesame oil. Plasma glucose, HbA1c, TC, LDL-C, and TG were decreased.TBARS level was reduced, while the activities of enzymic and the levels of nonenzymic antioxidants were increased. Plasmasodium levels were reduced, while potassium levels were elevated. These results indicate that substitution of sesame oil asthe sole edible oil has an additive effect in further lowering BP and plasma glucose in hypertensive diabetics.

FDM analysis for MHD flow of a non-Newtonian fluid for blood flow in stenosed arteries

D. S. Sankar,이우식 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.10

A computational model is developed to analyze the effects of magnetic field in a pulsatile flow of blood through narrow arteries with mild stenosis, treating blood as Casson fluid model. Finite difference method is employed to solve the simplified nonlinear partial differential equation and an explicit finite difference scheme is obtained for velocity and subsequently the finite difference formula for the flow rate, skin friction and longitudinal impedance are also derived. The effects of various parameters associated with this flow problem such as stenosis height, yield stress, magnetic field and amplitude of the pressure gradient on the physiologically important flow quantities namely velocity distribution, flow rate, skin friction and longitudinal impedance to flow are analyzed by plotting the graphs for the variation of these flow quantities for different values of the aforesaid parameters. It is found that the velocity and flow rate decrease with the increase of the Hartmann number and the reverse behavior is noticed for the wall shear stress and longitudinal impedance of the flow. It is noted that flow rate increases and skin friction decreases with the increase of the pressure gradient. It is also observed that the skin friction and longitudinal impedance increase with the increase of the amplitude parameter of the artery radius. It is also found that the skin friction and longitudinal impedance increases with the increase of the stenosis depth. It is recorded that the estimates of the increase in the skin friction and longitudinal impedance to flow increase considerably with the increase of the Hartmann number.

Solar power and desalination plant for copper industry: improvised techniques

Sankar, D.,Deepa, N.,Rajagopal, S.,Karthik, K.M. Techno-Press 2015 Advances in energy research Vol.3 No.1

In India, continuous production of electricity and sweet/potable water from Solar power and desalination plant plays a major role in the industries. Particularly in Copper industry, Solar power adopts Solar field collector combined with thermal storage system and steam Boiler, Turbine & Generator (BTG) for electricity production and desalination plant adopts Reverse osmosis (RO) for sweet/potable water production which cannot be used for long hours of power generation and consistency of energy supply for industrial processes and power generation cannot be ensured. This paper presents an overview of enhanced technology for Solar power and Desalination plant for Copper industry making it continuous production of electricity and sweet/potable water. The conventional technology can be replaced with this proposed technique in the existing and upcoming industries.

Two-fluid non-Newtonian models for blood flow in catheterized arteries - A comparative study

D. S. Sankar,Usik Lee 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.9

Steady flow of blood through catheterized arteries is studied by assuming the blood as a two-fluid model with the suspension of all the erythrocytes in the core region as a non-Newtonian fluid and the plasma in the peripheral layer as a Newtonian fluid. The non-Newtonian fluid in the core region of the artery is modeled as (i) Casson fluid and (ii) Herschel-Bulkley fluid. The expressions for the shear stress, velocity, flow rate, wall shear stress and flow resistance, obtained by Sankar and Lee (2008a, 2008b) for the two-fluid Casson model and two-fluid Herschel-Bulkley model are used to get the data for comparison. It is noticed that the plug flow velocity, velocity distribution and flow rate for the two-fluid H-B model are considerably higher than that of the two-fluid Casson model for a given set of values of the parameters. Further, it is found that the resistance to flow is significantly lower for the two-fluid H-B model than that of the two-fluid Casson model. Thus, the two-fluid H-B model is more useful than the two-fluid Casson model to analyze the blood flow through catheterized arteries.

Two -fluid nonlinear mathematical model for pulsatile blood flow through catheterized arteries

D. S. Sankar,이우식 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.6

The pulsatile flow of blood through a catheterized artery is analyzed, assuming the blood as a two-fluid model with the suspension of all the erythrocytes in the core region as a Herschel-Bulkley fluid and the peripheral region of plasma as a Newtonian fluid. The resulting system of the nonlinear implicit system of partial differential equations is solved by perturbation method. The expressions for shear stress, velocity, flow rate, wall shear stress and longitudinal impedance are obtained. The variations of these flow quantities with yield stress, catheter radius ratio, amplitude, pulsatile Reynolds number ratio and peripheral layer thickness are discussed. The velocity and flow rate are observed to decrease, and the wall shear stress and resistance to flow increase when the yield stress increases. The plug flow velocity and flow rate decrease, and the longitudinal impedance increases when the catheter radius ratio increases. The velocity and flow rate increase while the wall shear stress and longitudinal impedance decrease with the increase of the peripheral layer thickness. The estimates of the increase in the longitudinal impedance are significantly lower for the present twofluid model than those of the single-fluid model.

Two-Fluid Herschel-Bulkley Model for Blood Flow in Catheterized Arteries

D. S. Sankar,이우식 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.5

The steady flow of blood through a catheterized artery is analyzed, assuming the blood as a two-fluid model with the core region of suspension of all the erythrocytes as a Herschel-Bulkley fluid and the peripheral region of plasma as a Newtonian fluid. The expressions for velocity, flow rate, wall shear stress and frictional resistance are obtained. The variations of these flow quantities with yield stress, catheter radius ratio and peripheral layer thickness are discussed. It is observed that the velocity and flow rate decrease while the wall shear stress and resistance to flow increase when the yield stress or the catheter radius ratio increases when all the other parameters held constant. It is noticed that the velocity and flow rate increase while the wall shear stress and frictional resistance decrease with the increase of the peripheral layer thickness. The estimates of the increase in the frictional resistance are significantly much smaller for the present two-fluid model than those of the single-fluid model.

Microstructure, structural, optical and piezoelectric properties of BiFeO₃ nanopowder synthesized from sol-gel

Sankar Ganesh, R.,Sharma, S.K.,Sankar, S.,Divyapriya, B.,Durgadevi, E.,Raji, P.,Ponnusamy, S.,Muthamizhchelvan, C.,Hayakawa, Y.,Kim, D.Y. ELSEVIER 2017 Current Applied Physics Vol.17 No.3

<P>Nanocrystalline BiFeO3 (BFO) powder was synthesized by sol-gel method and subsequent annealed at 100-500 degrees C. The microstructural analysis of BFO nanopowder confirmed the perovskite like structure of spherical nanoparticles annealed at 500 degrees C. The Raman spectrum of BFO nanoparticles showed the rhombohedrally structure with the space group of R3c. The XPS spectrum of BFO nanopowder showed the peaks of Bi, Fe, and O at the binding energy of 158.8, 711.75 and 529.2 eV, respectively. The piezoelectric properties of BFO nanoparticles were evaluated by making the sandwiched structure of graphene/BiFeO3-PDMS/graphene. The fabricated piezoelectric device demonstrated an output voltage of 0.4 V by applying the normal pressure from human finger on the device. (C) 2016 Elsevier B.V. All rights reserved.</P>

Influence of slip velocity in Herschel-Bulkley fluid flow between parallel plates -A mathematical study

D. S. Sankar,Usik Lee 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.7

This theoretical study investigates three types of basic flows of viscous incompressible Herschel-Bulkley fluid such as (i) plane Couette flow, (ii) Poiseuille flow and (iii) generalized Couette flow with slip velocity at the boundary. The analytic solutions to the nonlinear boundary value problems have been obtained. The effects of various physical parameters on the velocity, flow rate, wall shear stress and frictional resistance to flow are analyzed through appropriate graphs. It is observed that in plane Poiseuille flow and generalized Couette flow, the velocity and flow rate of the fluid increase considerably with the increase of the slip parameter, power law index, pressure gradient. The fluid velocity is significantly higher in plane Poiseuille flow than in plane Couette flow. The wall shear stress and frictional resistance to flow decrease considerably with the increase of the power law index and increase significantly with the increase of the yield stress of the fluid. The wall shear stress and frictional resistance to flow are considerably higher in plane Poiseuille flow than in generalized Couette flow.

Numerical Study of Natural Convection in a Vertical Porous Annulus with an Internal Heat Source: Effect of Discrete Heating

Sankar, M.,Park, J.,Kim, D.,Do, Y. Taylor Francis 2013 NUMERICAL HEAT TRANSFER PART A-APPLICATIONS - Vol.63 No.9