Laboratory Study of Hydraulic Characteristics of Density Current with Phase Space Theory Analysis

Subject Areas : Water and river engineering

Mohammad Hosseini ^{1 *} , Mohammad Shabani ²

1 - Department of Civil Engineering, Meymand Center, Firoozabad Branch, Islamic Azad University, Firoozabad, Iran
2 - دانشگاه آزاد اسلامی واحد شیراز

Received: 2024-01-24 Accepted : 2024-03-16 Published : 2024-03-19

Keywords: Density current, Phase space, Trajectory, Absorber, Surrounding Dimension.,

Abstract :

Introduction: Density currents are created due to the entry of a heavier fluid into a lighter fluid due to the acceleration of the earth's gravity. Density current is non-linear in nature and is sensitive to initial conditions. The time evolution of the dense flow is expressed using trajectory lines in the phase space. The purpose of this research is to extract information hidden inside the system using the phase space theory regarding the evolution of the dense flow with changes in the hydraulic parameters of the dense flow input, so that the nature of the system and the formed pattern of the dense flow can be expressed in the bed of time. Materials and Methods: Density current was conducted with 28 different tests in a laboratory flume with a length of 8 m, a width of 35 cm and a height of 60 cm by changing the slope, concentration and inlet flow rate. In order to describe the system, using the phase space theory, the time signal was transmitted as an object in space, and the analysis in space replaced the analysis in time. Results and Discussion: With the increase of the slope, the data concentration is drawn on the semi-conductor and moves from top to bottom. When the inlet flow rate is 50 l/min, the concentration of the speed data is in the range of 2 cm/s to 4.5 cm/s, and it has taken on an absorbing state, and more chaos is seen in it. By changing the density from 1005 kg/m3 to 1010 kg/m3, the absorption of flow lines is reduced and the trajectories in the phase space diagram are more open and have more maxima. Conclusion: By increasing the slope from 1% to 3%, when the flume is without narrowing, its absorber is reduced and in fact it takes more time to reach the equilibrium and evolution of the phenomenon, but due to continuous or local narrowing, becomes more absorbent. In general, with the increase of the slope, the evolution of the flow occurs earlier. The system begins to saturate in the surrounding dimension of 13.8.

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