51. |
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52. |
- Bengtsson, Lars
(författare)
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Statisk istillväxt
- 1976
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Rapport (övrigt vetenskapligt/konstnärligt)
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53. |
- Bengtsson, Lars
(författare)
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Stochastic Modelling of Dispersion in the Lule River
- 1977
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Ingår i: Stochastic processes in water resources engineering. - Fort Collins, Colo. : Water resources publ.. ; , s. 153-166
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Konferensbidrag (refereegranskat)abstract
- Since turbulent diffusion is a stochastic phenomenon, it is hard to describe dispersion in a river deterministic formula, and no exact theory can be formulated. Simulation techniques are more promising in this respect. This paper described simulations of horizontal dispersion of tracer material from a finite and continuous source. A stochastic model by which the horizontal dispersion of a number of particles can be simulated was developed. The model accounts for the increased dispersion caused by horizontal shear. The input data required for the model were determined from field measurements carried out at four positions in the Lule River, after which the stochastic model was applied to an 8 km long reach of the river. It was found that Fickian Law of dispersion was not applicable since the dispersion coefficients grew still faster but were linear
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54. |
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55. |
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56. |
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57. |
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58. |
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59. |
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60. |
- Bengtsson, Lars
(författare)
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Wind Induced Circulation in Lakes
- 1978
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Ingår i: Nordic Hydrology. - : IWA Publishing. - 0029-1277 .- 1996-9694. ; 9:2, s. 75-94
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Tidskriftsartikel (refereegranskat)abstract
- In most lakes the wind is the most important flow generating mechanism. In this paper the problem of wind generated circulation - directly wind induced currents and seiches - in small lakes is reviewed. Many field observations are presented and discussed. In the thermocline and the hypolimnion forced seiche currents are shown to dominate the directly induced wind currents. Different kind of non-convective mathematical lake models are discussed and applied to different small lakes. Comparisons of observed and calculated currents show that lake models can be used to reproduce the currents of the upper 3–4 metres in a lake. The interaction between large-scale flow and turbulent flow is yet unknown, and therefore it is not possible to explain the physical current pattern and density anomalies at greater depth. In respect to the limited knowledge on turbulent processes in lakes, it is acceptable to apply a quadric relationship between wind stress and wind speed with a drag coefficient of about 1.0.10−3.
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