Journal of Basic and Applied Sciences  -   Volume 8 Number 2


Near and Intermediate Field Evolution of A Negatively Buoyant Jet

Raed Bashitialshaaer and Kenneth M. Persson

http://dx.doi.org/10.6000/1927-5129.2012.08.02.43

Abstract: In this study, a mathematical model was developed to simulate the jet and plume behavior in order to determine the optimum discharge conditions for different scenarios. The model was divided into two sub-models, describing respectively the near and intermediate field properties of the discharge for different inclinations and bottom slope. The lateral spreading and electrical conductivity was also described through a generalization of measured data. The predictions of the model were compared with experimental data collected in lab as well as results obtained with a commercial software CORMIX. A Matlab code was also developed describing the lateral spreading and centerline dilution of buoyant jet and plumes for near and intermediate field was developed. The model produces results in acceptable agreement with data and observations, even though some improvements should be made in order to give the correct weight to the bottom slope parameter and to reduce the need for user calibration. This study has limited result for only 16% bottom slope and 30 degrees inclination. Concentration was improved with the bottom slope by 10% than the horizontal bottoms and improved by about 40% with bottom slope together with inclination of 30 degrees.

Keywords: Lab-scale experiment, Turbulent jet, Negative buoyancy, Desalination, Brine

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The Effect of Grain Size on Radon Exhalation Rate in Soil Samples of Dera Ismail Khan in Pakistan

Tabassum Nasir and Nisar Ahmad

http://dx.doi.org/10.6000/1927-5129.2012.08.02.29

Abstract: Radon concentration and its exhalation rate has been measured from twenty five soil samples collected from seven different locations of Dera Ismail Khan, in the north west of Pakistan. These samples were crushed after drying and passed through sieves with different sizes of pores to get three grain sizes, £0.595 mm, 0.595-2.00 mm and 2.00-4.00 mm of soil. CR-39 based NRPB (National Radiological Protection Board) radon dosimeters have been used to measure the radon concentration and exhalation rates. The maximum average value of radon exhalation rate has found to be: (3.57±0.38) Bq m-2 hr-1 in the samples having grain size 2.00-4.00 mm and the minimum as: (2.21±0.26) Bq m-2 hr-1, in the samples with grain size £ 0.0595 mm. This indicates that the radon exhalation rate increases with the grain size. The maximum average value of radon exhalation rate has been found in samples collected from river side where soil texture is silty clay loam. The obtained values of radon exhalation rate for all the samples are well below the world average value of 57.60 Bq m-2 hr-1.

Keywords: Radon concentration, Radon exhalation rate, grain size, soil texture.

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