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Nayak, Ajit K.
- Evaluation of Variation of Instantaneous Velocity and Reynolds Stress Due to Spherical Obstruction in a Fluid Flow
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Authors
Affiliations
1 Irrigation and Drainage Engineering Division, Central Institute of Agricultural Engineering, Bhopal (M.P.), IN
1 Irrigation and Drainage Engineering Division, Central Institute of Agricultural Engineering, Bhopal (M.P.), IN
Source
International Journal of Agricultural Engineering, Vol 7, No 2 (2014), Pagination: 432-435Abstract
When a flow passes through a protruding particle, all the turbulent parameters of the fluid subjected to change. So the effect of flow past a protruding particle of spherical shape over a gravel bed was investigated experimentally. All experiments were performed in a 12 m in length, 0.9 m in width and 0.71 m deep horizontal flume. The slope was maintained at 1 in 1400, and depth of water level was 15 cm with gravel size of 2.6 mm. Three balls of 2cm, 3cm and 4cm diameter was kept in the test section as the protruding particle. The time-averaged velocity components were measured by the Acoustic Doppler Velocimeter (ADV), Vectrino. The point of interest lies in at 3d upstream and 0.5d, 1.0d, 1.5d, 2.5d, 3.5d, 5.5d, 8.0d downstream from the edge of the ball at various depth, where d is the diameter of the ball. At each section velocity measurements were taken at various vertical intervals. The experimental results have shown that the turbulent flow parameters affect significantly due to protruding particle. The velocity and the Reynolds stress of flow at bottom is negative at immediate downstream of the ball which reduces gradually till 2.5d downstream and both are fully recovered after 8d downstream of the section.Keywords
Turbulence, Flow Separation, Time Averaged Velocity, Reynolds Stress.
References
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- Estimation of Wind Load on a Greenhouse and Evaluation of its Structural Stability
Abstract Views :255 |
PDF Views:0
Authors
Affiliations
1 Irrigation and Drainage Engineering Division, Central Institute of Agricultural Engineering, Bhopal (M.P.), IN
1 Irrigation and Drainage Engineering Division, Central Institute of Agricultural Engineering, Bhopal (M.P.), IN
Source
International Journal of Agricultural Engineering, Vol 7, No 2 (2014), Pagination: 461-466Abstract
Among all the loads that act on the greenhouse, wind load is the major one. In India, the basic wind speed varies from 33 to 55 m/s. Along with wind speed, wind load also depend on the geometry, height to width ratio, effective frontal area etc. So greenhouse design should be customized as per the localized wind load. 'One size fits all approach' in greenhouse design may leads to failure of the structure or being expensive. Unfortunately the standard for greenhouse design is lagging far behind in India. In this experiment, wind load for the double arch type naturally ventilated greenhouse was estimated as per IS code 875 (part 3) and IS 14462: 1997. The design wind pressure estimated to be 772 N/m2 and wind load on the roof of the greenhouse is 222 kN (Suction) and 185 kN (Pressure). A model of the greenhouse is developed by means simulation with Finite Element Method using ANSYS 15.0 to test its stability at the calculated wind load. The truss and columns are studied with deflections and failure zones diagrams and possible failures were found out to redesign the elements.Keywords
Wind Load, Structural Stability, FEM, Pressure Co-Efficient, Truss.References
- Anonymous (2011). Greenhouse a reference manual, NCPAH, Ministry of Agriculture, Govt. of India.
- ANSYS, Inc. (2009). ANSYS Strcutural Analysis guide. ANSYS 15.0.
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- CEN (2003). EN 1991-1-4:2005-Eurocode-1: Actions on structures-Part 1-1-4: General actions - Wind actions 1-1-4. Comite Europeen de Normalisation, Brussels.
- IS 875: part 3 (1987). Code of practice for design load (other than earthquake) for buildings and structures.
- IS 14462: 1997. Recommendation for layout design and construction of greenhouse structure.
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- Singh, B. and Sirohi, N.P.S (2008). Protected cultivation of vegetable in India: problems and future prospects. Acta Hort., 710 : 339-342.
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- Von Elsner B., Briassoulis D., Waaijenberg D., Mistriotis A., Zabeltitz von Chr., Gratraud J., Russo G. and SuayCortes, R. (2000). Review of structural and functional characteristics of greenhouses in European Union countries: Part I, Design Requirements. J. Agric. Engg. Res., 75 : 1-16.
- Von Elsner, B., Briassoulis, D., Waaijenberg, D., Mistriotis, A., Zabeltitz von Chr., Gratraud J., Russo G. and SuayCortes R. (2000). Review of structural and functional characteristics of greenhouses in European Union countries: Part II, Design Requirements. J. Agric. Engg. Res., 75 : 111-126.