Ritesh Srivastava

Bio: Ritesh Srivastava is an academic researcher. The author has contributed to research in topics: Pressure drop & Nuclear engineering. The author has an hindex of 1, co-authored 1 publications receiving 10 citations.

Numerical Simulation of Vortex Shedding Past a Single Cylinder Confined in a Channel

Abstract: The vortex shedding past a circular cylinder in a two- dimensional channel of varying height is presented in the term of Strouhal number by solving continuity and momentum equations using FLUENT 6.3. The computational grid structure is generated by using Gambit. In this analysis, the result is carried out with blockage ratio b=80, 0.83, 0.85, 0.88 and Reynolds number range from 50 to 300

Radiation Analysis and Design Study of Unified Cooling and Baking Scheme for SMARTEX-C

Abstract: In this paper, a unified cooling and baking scheme has been designed and analyzed, which aids in maintaining the vacuum levels of an experimental system SMARTEX-C. It is a SMall Aspect Ratio Toroidal Experiment in a ‘C’ (SMARTEX-C) shaped geometry. It is a trap meant for confining electron plasma i.e. non-neutral plasma. A vacuum ∼ (1.5 ± 0.5) x 10−10 mbar is maintained inside the vessel. Electrons are emitted from a heated tungsten filament, which eventually deteriorates the vacuum of the vessel with time. To perform reproducible electron plasma experiments it is essential to maintain vacuum levels constant. The designed cooling scheme helps in maintaining it. Additionally, flow of hot Nitrogen has been incorporated in this scheme which serves baking of the vacuum vessel making the dedicated baking system redundant and makes the operation of the system hassle-free. The scheme is modeled in CATIA© and analyzed in ANSYS CFX©. The thermal-hydraulic performance has been analyzed and parametric results in terms of temperature, heat transfer coefficient and pressure drop have been provided for the cooling and baking of the vessel.

Effects of transverse magnetic field on a rotating micropolar fluid between parallel plates with heat transfer

Abstract: Hydromagnetic flow of a micropolar fluid between two horizontal parallel plates in a rotating system has been investigated. The governing partial differential equations for momentum, energy and micro-rotation are presented and transformed into ordinary differential equations by means of similarity transformations. The solutions for velocity, temperature and micro-rotation profiles are expressed through graphs against various emerging physical parameters such as coupling parameter, viscosity parameter, Hartman number, Reynold number, rotation parameter, porosity parameter and peclet number using optimal homotopy analysis method (OHAM). Local skin friction co-efficient and local heat fluxes are computed analytically using OHAM as well as numerically through mid-point integration scheme and they are found to be in excellent agreement. It has been observed that local skin friction is higher for the case of strong concentration compare to the case of weak concentration. Moreover, influence of strong and weak concentration on Nusselt number is also examined.

Probiotic capability in yeasts: Set-up of a screening method

Abstract: Microbial probiotic supplements are used to improve the health and wellness of people. For checking this ability (resistance to gastrointestinal conditions, auto-aggregation, cell surface hydrophobicity or biofilm formation abilities), it is crucial to evaluate some kinetics parameters. The objective of the present study was to establish an adequate method for studying the probiotic potential of Saccharomyces and non-Saccharomyces strains isolated from food ecosystems. A new protocol was designed based on kinetics parameters: lag phase (λ), generation time (G) and maximum OD (ODmax). The design was done using a step-by-step approach (up to 10 protocols), focusing on the choice of controls and the conditions to simulate the stomach and intestine. Each decision was made based on multifactorial statistical assay results. A preliminary screening indicates that protocol is adequate, quick and reproducible and that S. cerevisiae strains are more resistant than non-Saccharomyces ones. S. boulardii, (commercial control), was not one of the best yeasts evaluated. Thus, the most relevant results of the work are the setup of a new method for studying the survival/resistance of yeasts to the transit into the gut based on a complex statistical analysis of results and to mark the probiotic character in Saccharomyces yeasts versus non-Saccharomyces.

The Naturally Fermented Sour Pickled Cucumbers

Abstract: Naturally fermented sour pickled cucumbers belong to the products stabilized with salt and lactic acid. Factors affecting cucumber fermentation are discussed in this chapter since they have an impact on shelf-life, the nutritional and sensory value, flavor, digestibility, nutrient retention, and reduction of toxicity and antinutrient removal. During fermentation, lactic acid bacteria (LAB) synthesize several bacteriocins and liberate antimicrobial peptides, which are inhibitory to spoilage bacteria. Fermented cucumbers are microbiologically safe, nutritious, and flavorful, have appealing sensory characteristics, and can be conveniently stored for extended periods without refrigeration. Their health benefits are associated with probiotic LAB isolated from fermented cucumbers and their ability to produce bacteriocins. Fermented cucumber is also recognized as a source of macronutrients and starter cultures with high oligosaccharide productivity.

Stokes flow of an incompressible couple stress fluid confined between two eccentric spheres

Abstract: The quasi-steady translational motion of an incompressible couple stress fluid confined between two eccentric spherical surfaces is investigated. It is assumed that the motion is generated by allowing the internal sphere to translate with a constant velocity. The Stokesian assumption of low Reynolds numbers is considered so that the nonlinear terms of the equation of motion are neglected. The superposition principle is employed to construct the general solution of the governing equations in the presence of spherical surfaces using two spherical systems of coordinates relative to the centers of the two spherical surfaces. The no-slip boundary conditions on the spherical boundaries are applied. In addition, the conditions of vanishing couple stresses on the bounding surfaces are imposed. The boundary collocation technique is utilized numerically to satisfy the boundary conditions on the spherical surfaces. The drag force experienced by the fluid flow on the spherical particle is obtained and represented numerically through table and graphs. The numerical results show that the values of the drag force increases monotonically with the increase in the radii ratio. It increases also with the increase of the couple stress viscosity parameter. The obtained results are consistence with the results available in the literature for viscous fluids.