Thimmareddy G., Aswatha Reddy and Subrata Roy
This article attempts to study the influence of 1,2,3,4-Butane tetra carboxylic acid (BTCA)treatment on the properties of tassar silk fabric. Indian tassar (Anthrea mylitta D…
Abstract
This article attempts to study the influence of 1,2,3,4-Butane tetra carboxylic acid (BTCA)treatment on the properties of tassar silk fabric. Indian tassar (Anthrea mylitta D) silk fabrics have been treated with BTCA, a non-formaldehyde cross-linking agent, in the presence of sodium hypophosphite monohydrate as the catalyst and non-ionic polyethylene emulsion as the softener. Fabric shrinkage (dimensional stability) in the warp and weft directions shows significant improvement after treatment and also, a 10% improvement in the fabric crease recovery is observed. Although the single yarn strength is not significantly affected, the elongation of yarn decreases by 15%. Similarly, the fabric tensile strength and air permeability properties are the least affected, but the fabric tearing strength significantly increases after treatment with BTCA. The treatment displays promising results for tassar fabrics, which are inherently susceptible to shrinkage issues.
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B.V.K. SATYA SAI, K.N. SEETHARAMU, P.A. ASWATHA NARAYANA and J.N. REDDY
A finite element method based on the Eulerian velocity correction method has been used to analyse the laminar natural convection in an annular cavity. Unsteady, incompressible…
Abstract
A finite element method based on the Eulerian velocity correction method has been used to analyse the laminar natural convection in an annular cavity. Unsteady, incompressible, axisymmetric Navier‐Stokes equations have been made use of. Different radius ratios of the annular cavity have been considered to investigate the effect of the radius of curvature on the heat transfer coefficient.
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Sivasankaran Sivanandam and Bhuvaneswari Marimuthu
The numerical analysis is to scrutinize the collective effect of convective current along with the thermal energy transport in an inclined lid-driven square chamber with sine…
Abstract
Purpose
The numerical analysis is to scrutinize the collective effect of convective current along with the thermal energy transport in an inclined lid-driven square chamber with sine curve based temperature at the lower wall in the existence of unchanging external magnetic field. Insulation has been placed on the left and right of the box to increase the effective space volume of the shell. The thermal condition at ceiling wall is kept lower than the one on the floor.
Design/methodology/approach
The finite volume method employs to discretize (non-dimensional) system of equations govern the model. The heat transfer rate is measured by adjusting various variables, such as the Richardson number Hartmann number, inclination of an enclosure.
Findings
The flow behavior of enclosure convection is more highly influenced within the natural convection when enclosure inclination varies as well as magnetic field strength. The overall heat transfer rate decreases due to increase in both the Hartmann number as well as Richardson number.
Practical implications
The results of the present study are very useful to the cooling of electronic equipments.
Social implications
The study model is useful to the thermal science community and modelling field.
Originality/value
This research is a novel work on mixed convection flow in an inclined chamber with sinusoidal heat source.
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Ali J. Chamkha, B. Mallikarjuna, R. Bhuvana Vijaya and D.R.V. Prasada Rao
The purpose of this paper is to study the effects of Soret and Dufour effects on convective heat and mass transfer flow through a porous medium in a rectangular duct in the…
Abstract
Purpose
The purpose of this paper is to study the effects of Soret and Dufour effects on convective heat and mass transfer flow through a porous medium in a rectangular duct in the presence of inclined magnetic field.
Design/methodology/approach
Using the non-dimensional variables, the governing equations have been transformed into a set of differential equations, which are non-linear and cannot be solved analytically, therefore finite element method has been used for solving the governing equations.
Findings
The influence of thermo-diffusion, diffusion thermo, radiation, dissipation, heat sources and the inclined magnetic field on all the flow, heat and mass transfer characteristics has been found to be significant.
Originality/value
The problem is relatively original as it combines many effects as Soret and Dufour effects and chemical reaction under inclined magnetic field.
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Sahin Yigit and Nilanjan Chakraborty
This paper aims to numerically analyse natural convection of yield stress fluids in rectangular cross-sectional cylindrical annular enclosures. The laminar steady-state…
Abstract
Purpose
This paper aims to numerically analyse natural convection of yield stress fluids in rectangular cross-sectional cylindrical annular enclosures. The laminar steady-state simulations have been conducted for a range of different values of normalised internal radius (ri/L 1/8 to 16, where L is the difference between outer and inner radii); aspect ratio (AR = H/L from 1/8 to 8 where H is the enclosure height); and nominal Rayleigh number (Ra from 103 to 106) for a single representative value of Prandtl number (Pr is 500).
Design/methodology/approach
The Bingham model has been used to mimic the yield stress fluid motion, and numerical simulations have been conducted for both constant wall temperature (CWT) and constant wall heat flux (CWHF) boundary conditions for the vertical side walls. The conservation equations of mass, momentum and energy have been solved in a coupled manner using the finite volume method where a second-order central differencing scheme is used for the diffusive terms and a second-order up-wind scheme is used for the convective terms. The well-known semi-implicit method for pressure-linked equations algorithm is used for the coupling of the pressure and velocity.
Findings
It is found that the mean Nusselt number based on the inner periphery Nu¯i increases (decreases) with an increase in Ra (Bn) due to augmented buoyancy (viscous) forces irrespective of the boundary condition. The ratio of convective to diffusive thermal transport increases with increasing ri/L for both Newtonian (i.e. Bn = 0) and Bingham fluids regardless of the boundary condition. Moreover, the mean Nusselt number Nu¯i normalised by the corresponding Nusselt number due to pure conductive transport (i.e. Nu¯i/(Nu¯i)cond) shows a non-monotonic trend with increasing AR in the CWT configuration for a given set of values of Ra, Pr, Li for both Newtonian (i.e. Bn = 0) and Bingham fluids, whereas Nu¯i/(Nu¯i)cond increases monotonically with increasing AR in the CWHF configuration. The influences of convective thermal transport strengthen while thermal diffusive transport weakens with increasing AR, and these competing effects are responsible for the non-monotonic Nu¯i/(Nu¯i)cond variation with AR in the CWT configuration.
Originality/value
Detailed scaling analysis is utilised to explain the observed influences of Ra, BN, ri/L and AR, which along with the simulation data has been used to propose correlations for Nu¯i.
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P. Vasseur and G. Degan
Natural convection from a semi‐infinite vertical plate embedded in a fluid saturated porous medium is studied both analytically and numerically. The plate is assumed to be heated…
Abstract
Natural convection from a semi‐infinite vertical plate embedded in a fluid saturated porous medium is studied both analytically and numerically. The plate is assumed to be heated isothermally or by a constant heat flux. The porous medium, modeled according to Darcy’s law, is anisotropic in permeability with its principal axes oriented in a direction that is oblique to the gravity vector. In the large Rayleigh number limit, the governing boundary‐layer equations are solved in closed form, using a similarity transformation. Comparisons between the numerical solution of the full equations and analytical solutions are presented for a wide range of the governing parameters. The effects of the anisotropic permeability ratio K*, of the orientation angle of the principal axes θ, and of the Rayleigh number RH on the flow and heat transfer are investigated. Results indicate that the anisotropic properties of the porous medium considerably modify the heat transfer, velocity and temperature profiles from that expected under isotropic conditions.