Subsequently, ref. [16] performed a numerical study of the influence of an impeller with a regular blade and another with fractal blades on power consumption, and showed that fractal blades reduced torque compared to regular blades, since the drag coefficient of the fractal blade was distinctly lower than a regular blade. [PERSON] et al. [3] studied the effect of the number of blades for the impeller and different rotation speeds on the mixing efficiency and power consumption in a stirred tank. They concluded that the electrical power requirement for an impeller depended largely on the shape and the size of the impeller and, of course, the rotational speed. Moreover, an increase in mixing led to an exponential increase in the required power. Recently, ref. [17] studied the effect of different kinds of agitators on turbulent flow in stirred tanks, with and without baffles. The hydrodynamics behavior was induced by four different kinds of agitator: a Rushton turbine (RT), a circular blade turbine (CBT), a diverging triangular blade turbine (DTBT) and a converging triangular blade turbine (CTBT). In spite of the importance of baffles for the mixing of fluids in tanks, this kind of analysis is still very sparse in the literature. For instance, ref. [18] numerically studied two agitated tanks with and without baffles, varying the Reynolds number between laminar and turbulent flow in order to study the influence of these baffles on the power and pumping numbers. The authors concluded that, until a certain Reynolds number was achieved, the presence or not of baffles did not have a significant influence on the power. The magnitude of the power and pumping numbers started to differ in the presence of baffles when the flow was in transition, and drastically different values occurred in a totally turbulent flow. Subsequently, ref. [2] studied the influence of the stirred tank shape (cylindrical and polygonal) with and without baffles (vertical and circular baffles). A circular baffle has a format similar to a ring placed around the impeller and at a certain distance from the bottom of the tank. This ring was cut at different angles (\(20^{\circ}\), \(30^{\circ}\) and \(45^{\circ}\)), thus obtaining different size of baffles for each cutting angle. The authors concluded that the polygonal shape produced results similar to those of the cylindrical tank. In addition, the results showed that power consumption and vortex size decreased when the circular baffle was cut at an angle of \(20^{\circ}\). For the rectangular baffles, the power consumption was lower for tanks with only one baffle than two, three or four baffles. Despite the above mentioned investigations, few studies have investigated the effect of the geometrical configuration of the baffles on the mixing process and turbulent flow in stirred tanks, and even fewer have considered the application of constructal design [19; 20]. Constructal design is a method used to apply the physical principle of design to any finite-sized flow system. Constructal law states that for a finite-sized flow system to persist, i.e., to live, its design must evolve in such a way as to easily access the internal currents of the thermodynamic flow system [19; 21]. This unifying principle of design has been applied to predict designs in nature (trees, branches, vascular tissues and animal design), social organization (flow of goods, people and information and organizational structures) and engineering problems (renewable energy, fluid mechanics and heat transfer, heat exchangers, marine and aerodynamical structures and manufacturing processes) [22; 23]. Considering the wide applicability of constructal design, it is expected that this method can guide the theoretical recommendations for the influence of the design of rectangular baffles inserted in stirred tanks on mixture performance. More precisely, the present study has two main purposes.