Author(s): Masayuki Fujihara; Mai Akimoto; Subas Chhatkuli
Linked Author(s): Masayuki Fujihara
Keywords: Individual based model; Stochastic model; Shallow water equation; Thrust force; Burst speed
Abstract: This paper presents a numerical modelling of fish behaviour ascending in a fishway. The model is based on Newton’s 2nd Law with a random variable, which is introduced to express uncertainty of biological aspects. Two kinds of force which act on fish are considered. One is a drag force and the other is a thrust force. The thrust force has two kinds, one of which is used while cruising and the other while ascending rapid flow or escaping danger. When flow velocity around fish is greater than 80% of cruise speed, fish start to use the thrust force for swimming in burst speed. However fish can swim in burst speed for only a few seconds. The direction of thrust force is determined to be scattered around the opposite direction of flow according to the random variable which follows the normal distribution. The model is run in a computed flow field of vertical slot fishway and shows the ascending ratio of fish increase as body length of fish increase. Computed trajectories of fish are similar to the patterns which ascending fish show.
Year: 2005