CFD Analysis of conjugate natural convection in a vertical annulus

Conjugate natural convection in a vertical annulus with a centrally located vertical heat generating rod is studied numerically. The governing equations are discretized on a staggered mesh and are solved using a pressure-correction algorithm. A parametric study is performed by varying the Grashof number, aspect ratio, and the solid-to-fluid thermal conductivity ratio over wide ranges with the Prandtl number fixed at 0.7. Results are presented for the variation of several quantities of interest such as the local Nusselt numbers on the inner and outer boundaries, the axial variation of the centerline and interface temperatures, maximum solid, average solid and average interface temperature variations with Grashof number, and the average Nusselt number variation for the inner and outer boundaries with Grashof number. The average Nusselt number from the conjugate analysis is found to be between the Nusselt numbers of the isothermal and the isoflux cases. The average Nusselt numbers on the inner and outer boundaries show an increasing trend with the Grashof number. Correlations are presented for the Nusselt number and the dimensionless temperatures of interest in terms of the parameters of the problem

Non-Boussinesq conjugate natural convection in a vertical annulus

Non-Boussinesq conjugate natural convection in a vertical annulus with a centrally located vertical heat generating rod is studied numerically, taking into account variable transport properties. Results are presented for maximum solid temperatures, average Nusselt numbers and average pressure. In general, the Boussinesq model predicts higher temperatures in the solid and lower average Nusselt numbers on the inner and outer boundaries. (C) 2010 Elsevier Ltd. All rights reserved

Nanometric chemical decomposition of infertile Himalayan soils from Uttarakhand

We present the nanometric chemical decomposition of Himalayan agricultural soils. The motivation to use this state-of-the-art material characterisation in the soil is to reduce the testing cost while increasing the efficiency of the characterisation. In India, a bulk volume of soil is still required for the characterisation of agricultural soil. The fertility of micronutrient contents and crop supply capacity vary greatly depending on soil types, crop types, ecology, and agroclimatic variability. Since total levels of micronutrients are rarely predictive of the availability of a nutrient to plants, knowledge of the differences in soil micronutrients that are available to plants is essential for the sensible management of micronutrient fertility and toxicity. In the state of Uttarakhand, low levels of micro-nutrients in the soil are frighteningly common, and this issue is made worse by the fact that many current cultivars of important crops are extremely vulnerable to low mineral levels. These baseline results are to be used to inform local farmers about the potential remedies, costs, and consequential benefits and durability. We intend not to present a generalized or generalized solution. Therefore, we limit our soil sample collections to five arc minutes (8.6 square kilometers) and document variations and heterogeneity in the chemical components of the soil. In this study, we used scanning electron microscopy to chemically deconstruct the barren Himalayan soils from Uttarakhand. Aluminium, carbon, oxygen, and silicon were identified as the primary elements that contributed more than 5% of the total weight and atomic percentage. Other elements include less than 4% of iron, titanium, nitrogen, sodium, magnesium, chloride, phosphorus, sulfur, potassium, and calcium

Hypertension and hyperparathyroidism are associated with left ventricular hypertrophy in patients on hemodialysis

Conflicting data for association between left ventricular hypertrophy (LVH) and secondary hyperparathyroidism has been reported previously among dialysis patients. The present study was conducted to evaluate the association of hyperparathyroidism and hypertension with LVH. Charts of 130 patients on hemodialysis for at least six months were reviewed. All were subjected to M-mode echocardiography. Left ventricular mass (LVM) was calculated by Devereux's formula. LVM Index (LVMI) was calculated by dividing LVM by body surface area. Sera were analyzed for intact parathyroid hormone (iPTH). iPTH of > 32 pmol/l and a mean blood pressure (MAP) of > 107 mmHg were considered high. Patients were stratified into groups according to their MAP and iPTH. A total of (47.7%) patients were males and 68 (52.3%) were females. Their median age was 57 years. The median duration on dialysis was 26 months. Forty eight (36.9%) patients had high BP and 54 (41.5%) had high iPTH. Both high BP and high iPTH were present in 38 (29.2%) patients. Analysis of the relationship between LVM, LVMI, MAP and iPTH showed that LVM and LVMI were significantly (P < 0.001) higher in patients with concomitant high BP and high iPTH. LVMI was significantly higher in patients with high iPTH alone. Concomitant high iPTH and high MAP increase the risk of LVH in hemodialysis patients. High iPTH alone might contribute in escalating LVH. Adequate control of hypertension and hyperparathyroidism might reduce the risk of developing LVH