5
Abstract
Aquaculture is a permanent source of seafood for human consumption. However, this
production technique has its disadvantages, since fish farms have been accused of
degrading the surrounding ecosystems. Therefore, modeling is an advantageous tool to test
different variabilities in aquaculture engineering in order to develop a sustainable
aquaculture. Indeed, the use of numerical tools is essential in aquaculture, it intervenes at
several scales; from modeling the velocities flow in the farming tanks, to the study of the
interactions between the fish farms and the environment.
The aim of this work is based on the use of modeling to simulate velocities and
temperature in a circular, rectangular and a new design of rearing tanks and also to assist
authorities in the selection and evaluation of aquaculture sites. Numerical tools are
therefore used to:
o simulate flow velocities and temperature in existing and in a new farming tank
design ;
o quantify the farm effluents and simulate their dispersion ;
o study the effect of hydrodynamic parameters on the dispersion of the farm
effluents.
First, the Ansys Fluent numerical tool was chosen to simulate seawater flow velocities and
temperatures in the most used fish farming tanks as well as in a new tank design. Then, the
Mike 21 software is used to study the effect of hydrodynamic parameters on the dispersion
of discharges from a virtual aquaculture farm located in the West coast of Algeria. The
nutritional effluents are estimated from the indirect method defined by the Roque
d’Orbaquastel equations implemented in Matlab.
The results of velocity simulations in the tanks are within an acceptable range for fish
farming (with an inlet diameter of 0.15 m and 40 cm/s as an inlet velocity) which confirms
the importance of the geometry, location and number of water inlets and outlets as well as
the water flow. Indeed, the new rearing design provides acceptable velocity profiles for
fish farming (3-40 cm/s).
In addition, the virtual farm studied is characterized by particulate effluents concentrations
(0.02-0.45 mg/l) and dissolved discharge concentrations (0.16-2.1 mg/l for the nitrogen
and 0.002-0.03 mg/l for the phosphorus) related to the amounts of distributed food. These
discharges are within the limits tolerated by the Algerian authorities for industries
effluents.
Keywords: Ansys Fluent, Mike 21, modeling, aquaculture engineering, sustainable
aquaculture.
Abstract
Aquaculture is a permanent source of seafood for human consumption. However, this
production technique has its disadvantages, since fish farms have been accused of
degrading the surrounding ecosystems. Therefore, modeling is an advantageous tool to test
different variabilities in aquaculture engineering in order to develop a sustainable
aquaculture. Indeed, the use of numerical tools is essential in aquaculture, it intervenes at
several scales; from modeling the velocities flow in the farming tanks, to the study of the
interactions between the fish farms and the environment.
The aim of this work is based on the use of modeling to simulate velocities and
temperature in a circular, rectangular and a new design of rearing tanks and also to assist
authorities in the selection and evaluation of aquaculture sites. Numerical tools are
therefore used to:
o simulate flow velocities and temperature in existing and in a new farming tank
design ;
o quantify the farm effluents and simulate their dispersion ;
o study the effect of hydrodynamic parameters on the dispersion of the farm
effluents.
First, the Ansys Fluent numerical tool was chosen to simulate seawater flow velocities and
temperatures in the most used fish farming tanks as well as in a new tank design. Then, the
Mike 21 software is used to study the effect of hydrodynamic parameters on the dispersion
of discharges from a virtual aquaculture farm located in the West coast of Algeria. The
nutritional effluents are estimated from the indirect method defined by the Roque
d’Orbaquastel equations implemented in Matlab.
The results of velocity simulations in the tanks are within an acceptable range for fish
farming (with an inlet diameter of 0.15 m and 40 cm/s as an inlet velocity) which confirms
the importance of the geometry, location and number of water inlets and outlets as well as
the water flow. Indeed, the new rearing design provides acceptable velocity profiles for
fish farming (3-40 cm/s).
In addition, the virtual farm studied is characterized by particulate effluents concentrations
(0.02-0.45 mg/l) and dissolved discharge concentrations (0.16-2.1 mg/l for the nitrogen
and 0.002-0.03 mg/l for the phosphorus) related to the amounts of distributed food. These
discharges are within the limits tolerated by the Algerian authorities for industries
effluents.
Keywords: Ansys Fluent, Mike 21, modeling, aquaculture engineering, sustainable
aquaculture.