Numerical Simulation of Air Diffusion in Water with Venturi Type Injector for Applications in Freshwater Aquaculture Biofloc Systems

• Main Author: Yulianto, Eri
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/43686
• Institution: Institut Teknologi Bandung

Indonesia has a large potential of fishery resources, both in capture fisheries and freshwater aquaculture resources. In freshwater aquaculture activities, oxygen supply becomes an important thing that must be fulfilled. Oxygen supply is important to fulfill the needs of fish respiration, decompose the ammonia, and maintain water quality. As technology develops, there is an efficient system of freshwater aquaculture namely biofloc system that utilizes oxygen supply and the addition of probiotics and carbon sources to process ammonia into feed with the help of microorganisms. The oxygen needs can be fulfilled with an aerator, with one of the aerator types that is venturi type injector. The working principle of venturi type injector is to create a different pressure between pressures of the outside air and pressures of the fluid in the pipe until it reach the vacuum point of pressure therefore the air will be absorbed into the venture. Because the flow at the venturi outlet is turbulent, water and air will be mixed, then air bubbles will form. The smaller the bubble size, it will have a low rising velocity and will remain in the water longer so that it can increase the DO (dissolved oxygen) or oxygen content in the water. This bachelor thesis conducted a simulation of venturi air injector type with variations of volumetric flowrate parameter of 13 lpm, 15 lpm, and 17 lpm to see the airflow in the water. Numerical simulations were assessed with ANSYS Fluent software. Result of the airflow that obtained through numerical simulations are rising velocity of 224 mm/s for volumetric flowrate of 13 lpm, rising velocity of 119 mm/s for volumetric flowrate of 15 lpm, and rising velocity of 56.9 mm/s for volumetric flowrate of 17 lpm. Therefore, it can be concluded that the higher the value of volumetric flowrate, the rising velocity of air in the water will be smaller.