水动力学条件对鱼类生长影响的试验研究
Experimental study of the effect of hydrodynamic conditions on fish growth
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摘要: 以鲫鱼为研究对象,将其放入流速渐变环形水槽的不同水动力分区中进行实验,研究水动力学条件对鱼类生长的影响。通过对水槽流场的三维数值模拟,得到其中与鲫鱼生长相联系的水动力学细部特征,将模拟结果与实测流场数据比较分析,结果可靠。细部特征采用流速、流速梯度和动能梯度3个水动力学特征量进行量化分析,并结合鲫鱼相对日增长率,得到鱼类生长与水动力学特征量之间的定量关系。流速对鲫鱼有一个短期的胁迫作用,0.20m/s流速比较适宜鲫鱼的生长;鲫鱼的体重相对日增长率随着水流动能梯度增大而下降,两者呈现负相关性,0.009J/(kg·m)为鲫鱼生长所需动能梯度的一个阈值。通过量化鱼类生长对水动力学条件的需求,可为生态水利规划提供定量化的依据。Abstract: To find out the appropriate hydrodynamic conditions for fish growth is an important issue in present eco-hydraulic research. The experimental study presented here is to investigate the effect of the hydrodynamic conditions on fish growth. Especially, the Carassius auratus is chosen here for the case study through taking segmentation experiments in the graded ring shape flume. The detailed hydrodynamic characteristics of flumes which are relevant to fish growth are obtained through the 3D numerical simulation of the flume's flow field. Compared with the simulation results and the on-site measurements, the simulation is shown to be reliable. Combining the relative daily growth rate of Carassius auratus with the flow detail characteristics which are quantized by three hydrodynamic characteristic variables including flow velocity, velocity gradient and kinetic energy gradient, the quantitative relationship is established between the fish growth and the hydrodynamic characteristic variables. There is a short-term effect of flow velocity stress on the growth of Carassius auratus, and 0.2m/s is a very feasible velocity for the growth of Carassius auratus. A negative correlation is found between the relative daily growth rate and the kinetic energy gradient with the relative daily growth rate decreasing with the increase of kinetic energy. The threshold of kinetic energy gradient of the growth of Carassius auratus is 0.009J/(kg·m).The quantification of the hydrodynamic conditions of fish growth can provide the quantitative basis for the ecological water conservancy planning.