10 research outputs found
Large-eddy simulations of a turbulent jet impinging on a vibrating heated wall
Get PDFHigh-resolution large-eddy simulations (LES) are performed for an incompressible turbulent circular jet impinging upon a vibrating heated wall supplied with a constant heat flux. The present work serves to understand the flow dynamics and thermal characteristics of a turbulent jet under highly dynamic flow and geometric conditions. The baseline circular vibrating-wall jet impingement configuration undergoes a forced vibration in the wall-normal direction at the frequency, f = 100 Hz. The jet Reynolds number is = 23,000 and the nozzle-exit is at y/D = 2 where the wall vibrates between 0 and 0.5D with amplitude of vibration, A = 0.25D. The configuration is assembled through validation of sub-systems, in particular the method for generating the turbulent jet inflow and the baseline circular jet impingement configuration. Both time-mean and phase-averaged results are presented. The mean radial velocity increases upon positive displacement of the wall and decreases upon negative displacement but this correlation changes with increased radial distance from the stagnation point. Vortical structures are shown to play a major role in convective heat transfer even under the vibrating conditions of the impingement wall. Periodic shifts in the secondary Nusselt number peak are observed that depend upon the travelling eddy location and strength of large-eddy structures. Enhancement in heat transfer is seen in the stagnation region but this beneficial effect of vibration on heat transfer is confined to the impingement region, r/D < 1.5
An integrated organic farming system: innovations for farm diversification, sustainability, and livelihood improvement of hill farmers
Get PDFIntroductionOrganic farming is a promising solution for mitigating environmental burdens related to input-intensive agricultural practices. The major challenge in organic agriculture is the non-availability of large quantities of organic inputs required for crop nutrition and sustaining soil health, which can be resolved by efficient recycling of the available on- and off-farm resources and the integration of the components as per the specific locations.MethodsAn integrated organic farming system (IOFS) model comprising agricultural and horticultural crops, rainwater harvesting units, livestock components, and provisions for nutrient recycling was developed and disseminated in the adopted organic villages Mynsain, Pynthor, and Umden Umbathiang in the Ri-Bhoi District, Meghalaya, India, to improve the income and livelihood of farmers. Harvested rainwater in farm ponds and Jalkunds was used for live-saving irrigation in the winter months and diversified homestead farming activities, such as growing high-value crops and rearing cattle, pigs, and poultry.ResultsMaize, french bean, potato, ginger, tomato, carrot, and chili yields in the IOFS model increased by 20%−30%, 40%−45%, 25%−30%, 33%−40%, 45%−50%, 37%−50%, and 27%−30%, respectively, compared with traditional practices. Some farmers produced vermicompost in vermibeds (made of high-density polyethylene) and cement brick chambers, generating 0.4−1.25 tons per annum. Two individual farmers, Mr. Jrill Makroh and Mrs. Skola Kurbah obtained net returns (without premium price) of Rs. 46,695 ± 418 and Rs. 31,102 ± 501 from their respective 0.27- and 0.21-ha IOFS models, which is equivalent to Rs. 172,944 ± 1,548/ha/year and Rs. 148,105 ± 2,385/ha/year, respectively. The net returns obtained from the IOFS models were significantly higher than those obtained from the farmers' practice of maize-fallow or cultivation of maize followed by vegetable (~30% of the areas). It is expected that, with the certification of organic products, the income and livelihood of the farmers will improve further over the years. While Mr. Jrill Makroh's model supplied 95.1%, 82.0%, and 96.0% of the total N, P2O5, and K2O, respectively, needed by the system, Mrs. Skola Kurbah's model supplied 76.0%, 68.6%, and 85.5% of the total N, P2O5, and K2O, respectively.DiscussionThus, IOFS models should be promoted among hill farmers so that they can efficiently recycle farm resources and increase their productivity, net returns, and livelihood while reducing their dependence on external farm inputs
