The construtal theory is an idea that says the generation of flow configuration is a physical phenomenon. This theory is explains that, “for a flow system to persist in time it must evolve in such a way that it provides easier and easier access to the currents that flow through it.” Actually, this theory pays attention to the geometry and configuration of the flow systems. A well-known structure of constructal theory aided design is the tree-shaped network. The cooling of electronics is done by three mechanisms of heat transfers: conduction, convection, and radiation. In convective cooling, two goals are targeted: first, optimizing thermal resistance, and second, optimizing flow resistance. In fact, the constructal theory leads to the optimal geometrical features of flow paths, so that the resistances (thermal resistance and flow resistance) are minimized. In this research, the flow paths are designed between some points located equidistantly on an internal ring and some other points located equidistantly on an external ring. The fluid enters the conduits at the internal ring, flows outward and exists at the edge of the disc. The coolant is single-phase, and the regime of fluid flow is laminar and fully-developed in every channel. The heat generation throughout the body is uniform while the global volume of channels is constrained. In the present thesis, Y- shaped structures with pairing or bifurcation emdedding in a disc body were investigated. The disc of this study has non-dimensional internal radius 0.0, 0.1, 0.2 and 0.3. The best geometric notions of tree-shaped structures are sought to have the minimal overall flow and thermal resistances. The overall flow resistance constitutes of two parts: (i) distributed pressure losses and (ii) local pressure losses. In this work, the effect of various parameters upon these resistances and hence the thermal and flow performances are investigated. These parameters include number of ducts initiating from the internal ring, number of branching, internal radius of disc and mass flow rate. From the results, it is disclosed that among the different parameters affecting the resistances, the mass flow rate has the most effect on thermal resistance; whilst, the effect of mass flow rate on the flow resistance is slight. Moreover, it is seen that increasing the complexity (more levels of pairing) lead to the reduction of the thermal resistance and increment of the flow resistance. Also, it was found out that the increasing of internal radius is led to the decrease in both thermal and flow resistances. Keywords: Constructal Theory, Thermal Resistance, Flow Resistance, Tree Networks, Electronics Cooling, Geometric Features, Convection, Optimization.