Vikas Kannojiya

Bio: Vikas Kannojiya is an academic researcher from Indian Institute of Technology Roorkee. The author has contributed to research in topics: Slurry & Impeller. The author has an hindex of 5, co-authored 11 publications receiving 46 citations. Previous affiliations of Vikas Kannojiya include Thapar University & Shree Guru Gobind Singh Tricentenary University.

Numerical simulation of centrifugal and hemodynamically levitated LVAD for performance improvement

Abstract: Left ventricular assist device (LVAD) provides an effective artificial support system to the heart patients. Despite the improved life survival rate, complications like hemolysis, blood trauma, and thrombus formation still limit the performance of the blood pump. The geometrical aspects of blood pumps majorly influence the hemodynamics, therefore these devices must be carefully engineered. In this work, several versions of centrifugal blood pumps are simulated using ANSYS-CFX to propose a best compatible design for LVAD. A hemodynamic levitation approach for the impeller is also suggested to overcome the cost and weight issue associated with the magnetic levitation. The blood flow is modeled by implementing Bird-Carreau model and its turbulence is solved using the SST turbulence model. The influence of the blade profile, blade tip width, blade numbers, and splitter blades on the hemodynamic characteristics through the pump is observed. An optimum design of centrifugal blood pump for the assistance of failed ventricle is proposed that can effectively pump the blood from the left ventricle to the ascending aorta. The proposal can be adopted by LVAD designers to have hemodynamically tuned efficient product.

Solar Energy a Path to India’s Prosperity

Abstract: Solar energy technology has grabbed a worldwide interest and attention these days. India also, having a huge solar influx and potential, is not falling back to feed its energy demand through non-conventional energy sources such as concentrating solar power (CSP) and photovoltaic (PV). This work will try to add some comprehensive insight on solar energy framework, policy, outlook and socio-economic challenges of India. This includes its prominent areas of working such as grid independent and ‘utility-scale’ power production using CSP or PV power plants, rural as well as urban electrification using PV, solar powered public transportation systems, solar power in agrarian society—water pumping, irrigation, waste management and so on and so forth. Despite the fact that, a vast legion of furtherance and advancement has been done during the last decade of solar energy maturation and proliferation, improvements could be suggested so as to augment the solar energy usage in contrast to conventional energy sources in India.

Simulation of Blood as Fluid: A Review From Rheological Aspects

Abstract: Blood flow in the human vascular system is a complex to understand example of fluid dynamics in a closed conduit. Any irregularities in the hemodynamics may lead to lethal cardiovascular disease like heart attack, heart failure and ischemia. Numerical simulation of hemodynamics in the blood vessel can facilitate a thorough understanding of blood flow and its interaction with the adjacent vessel wall. A good simulation approach for blood flow can be helpful in early prediction and diagnosis of the mentioned disease. The simulation outcomes may also provide decision support for surgical planning and medical implants. This study reports an extensive review of various approaches adopted to analyze the influence of blood rheological characteristics in a different class of blood vessels. In particular, emphasis was given on the identification of best possible rheological model to effectively solve the hemodynamics inside different blood vessels. The performance capability of different rheological models was discussed for different classes and conditions of vessels and the best/poor performing models are listed out. The Carreau, Casson and generalized power-law models were appeared to be superior for solving the blood flow at all shear rates. In contrast, power law, Walburn-Scheck and Herchel-Bulkley model lacks behind in the purpose.

Proposal of hemodynamically improved design of an axial flow blood pump for LVAD.

Abstract: Left ventricular assist devices (LVAD) emerges as an effective clinical device providing life-saving support to heart patients. The design of blood pump of an LVAD involves incredible accuracy and thorough understanding of hemodynamics to mimic the functionality of a healthy ventricle. This work studies hemodynamics around an LVAD and proposes an improved model of axial blood pump for cardiac circulation without any hemolysis complications through numerical investigations. A three-dimensional study on different versions of the impeller with three curved blades (pump I) and spiral blade (pump II) is carried out by utilizing computational fluid dynamics software ANSYS-CFX at a range of rotational speeds and flow rates. The non-Newtonian blood flow through pump is modeled by using Bird-Carreau model. To capture the change in the flow field near the rotating blade, a transient blade row model was employed. The proposal of spiral blade impeller was found to be more compatible as per the hemolytic performance. It considerably reduces the blood damage to two times lesser value than that by pump I and also improves the quality blood flow field. The spiral blade provides a guiding path to the blood particle and avoids mixing of different bloodstreams, thus reducing the eddy losses. Graphical abstract The graphical abstract shows the performance enhancement of the axial blood pump. The model proposed by Peng et al. (Comput Methods Biomech Biomed Engin 17(7):723-727, 2014) has been upgraded to two new versions by redesigning its impeller. Proposed design (pump II) shows improvement in pressure distribution (a) and reduction in hemolysis (in the case of pump II) index (b).

Numerical methods for engineers

Abstract: The fifth edition of "Numerical Methods for Engineers" continues its tradition of excellence. Instructors love this text because it is a comprehensive text that is easy to teach from. Students love it because it is written for them--with great pedagogy and clear explanations and examples throughout. The text features a broad array of applications, including all engineering disciplines. The revision retains the successful pedagogy of the prior editions. Chapra and Canale's unique approach opens each part of the text with sections called Motivation, Mathematical Background, and Orientation, preparing the student for what is to come in a motivating and engaging manner. Each part closes with an Epilogue containing sections called Trade-Offs, Important Relationships and Formulas, and Advanced Methods and Additional References. Much more than a summary, the Epilogue deepens understanding of what has been learned and provides a peek into more advanced methods. Approximately 80% of the end-of-chapter problems are revised or new to this edition. The expanded breadth of engineering disciplines covered is especially evident in the problems, which now cover such areas as biotechnology and biomedical engineering. Users will find use of software packages, specifically MATLAB and Excel with VBA. This includes material on developing MATLAB m-files and VBA macros.

A review of recent advances in tribology

Abstract: The reach of tribology has expanded in diverse fields and tribology related research activities have seen immense growth during the last decade. This review takes stock of the recent advances in research pertaining to different aspects of tribology within the last 2 to 3 years. Different aspects of tribology that have been reviewed including lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology. This review attempts to highlight recent research and also presents future outlook pertaining to these aspects. It may however be noted that there are limitations of this review. One of the most important of these is that tribology being a highly multidisciplinary field, the research results are widely spread across various disciplines and there can be omissions because of this. Secondly, the topics dealt with in the field of tribology include only some of the salient topics (such as lubrication, wear, surface engineering, biotribology, high temperature tribology, and computational tribology) but there are many more aspects of tribology that have not been covered in this review. Despite these limitations it is hoped that such a review will bring the most recent salient research in focus and will be beneficial for the growing community of tribology researchers.

Shear stress and blood trauma under constant and pulse-modulated speed CF-VAD operations: CFD analysis of the HVAD.

Abstract: Modulation of pump speed has been proposed and implemented clinically to improve vascular pulsatility in continuous flow ventricular assist device patient. The flow dynamics of the HVAD with a promising asynchronous pump speed modulation and its potential risk for device-induced blood trauma was investigated numerically. The boundary conditions at the pump inlet and outlet were defined using the pressure waveforms adapted from the experimentally recorded ventricular and arterial pressure waveforms in a large animal ischemic heart failure (IHF) model supported by the HVAD operated at constant and modulated pump speeds. Shear stress fields and hemolysis indices were derived from the simulated flow fields. The overall features of the computationally generated flow waveforms at simulated constant and pulse-modulated speed operations matched with those of the experimentally recorded flow waveforms. The simulations showed that the shear stress field and hemolysis index vary throughout the cardiac cycle under the constant speed operation, and also as a function of modulation profile under modulated speed operation. The computational model did not demonstrate any differences in the time average hemolysis index between constant and modulated pump speed operations, thereby predicting pulse-modulated speed operation may help to restore vascular pulsatility without any further increased risk of blood trauma.

Biodegradable and Compostable Plastics: A Critical Perspective on the Dawn of their Global Adoption.

Abstract: The global adoption of biodegradable and compostable plastics obtained from biomass-derived monomers, we argue in this account, is now close to the inflection point. The first industrially significant impact will affect the packaging segment of the global chemical industry. In this process, China and India will play a pivotal role. Selected guidelines aiming to foster development of bioplastics industry in both developed and developing nations are provided.