فهرست مطالب homayoon emdad

Turbinates play an important role in conditioning of inhaled air and affect the air flow passing the nasal cavity. The purpose of this study is to investigate the effect of removing inferior turbinate on flow field, heat and moisture transfer from mucosa into the inhaled-air in a human nasal cavity and comparison of them before and after the surgery. Turbinectomy was performed virtually on the computational model under the specialist’s supervision. In this study the airflow assumed to be laminar and unsteady. The nasal wall assumed to be rigid and no slip boundary condition was set. Moreover, the mucous layer assumed to be within fixed thickness in all over nasal cavity surface. The temperature and humidity distribution over the surface of mucusa are found by numerical computation. The results depict that conditioning of the nasal airway deteriorates by removing the inferior turbinate. For a specific air flow rate, both the heat and moisture flux averages decrease after surgery.

Piezoelectric Energy harvesting (PEH) from fluid flow energy has attracted significant attention throughout the last decade. In the previous PEH from fluid flow, a piezoelectric beam placed behind a bluff body such as circular cylinders. Hence, the piezoelectric beam oscillated due to the vortex shedding behind of the bluff body. Subsequently, this vibration generates voltage in the beam. In many engineering vehicles such as airplanes the strong vortex shedding caused by bluff body is destructive and reduces the efficiency of devices, therefore; it is not proper to attach a bluff body to these devises.
In this paper PEH from vertical beams in low speeds and high speed flows are investigated. Current work shows that in contrast to the low speed flows the extracted power from vertical beam in the high speed flows are considerable. Moreover, for a practical example of vertical beam in high speed flows the energy harvesting from piezoelectric Gurney flap attached to a NACA2412 airfoil is investigated. Finally, this study proposes a piezoelectric vertical beam with attached end cylinder as an energy harvester in the low speed flows. It is indicated that this device has strong vibration and therefore produces a remarkable electrical power

In this article the possibility to use Eulerian approach in the conventional ISPH method in simulation of internal fluid flows is studied. The use of Eulerian approach makes it possible to use non uniform particle distributions to increase the resolution in the sensitive parts of the domain, different boundary conditions can be employed more freely and particle penetration in the solid walls and tensile instability no longer require elaborate procedures. The governing equations are solved in an Eulerian framework containing both the temporal and local derivatives which make the momentum equations non-linear. Some special treatment and smaller time steps are required to remedy this non-linearity of the problem. In this study, projection method is used to enforce incompressibility with the evaluation of an intermediate velocity and then this velocity is projected on the divergence-free space. This method is applied to the internal fluid flows in a shear-driven cavity, Couette flow, a flow inside a duct with variable area and flow around a circular cylinder within a constant area duct. The results are compared with the results of Lagrangian ISPH and WCSPH methods as well as finite volume and Lattice Boltzmann grid based schemes. The results of the studied scheme have the same accuracy for velocity field and have better accuracy in pressure distribution than ISPH and WCSPH methods. Non-uniform particle distributions are also studied to check the applicability of this method and Good agreement is also observed between uniform and non-uniform particle distributions.

In this article, a forced reduced-order modeling approach, suitable for active optimal control of fluid dynamical systems based on the Proper Orthogonal Decomposition and perturbation method on the Reynolds-Averaged Navier-Stokes equations is presented. Numerical simulation of turbulent flow equations is too costly for the purpose of optimization and control of unsteady flows. As a result, POD/Galerkin projection and perturbation method on the RANS equations is considered. Using perturbation method, the controlling parameter shows up explicitly in the forced reduced-order system. The feedback control of the controlling parameter is one of the objectives of this study. With the perturbation method, the effect of the controller is sensed by fluid flow in each time step. The effectiveness of this method has been shown on optimal control of re-circulation problem for the turbulent flow over step with blowing/suction controlling jets. Actuators are positioned at two different locations—blowing/suction jets at the foot and edge of the step and blowing/suction jets at the wall of the step. Results show that perturbation method is fast and accurate in estimating the re-circulated turbulent flow over step. It is concluded that blowing/suction jets at the wall of the step are more efficient in mitigating flow separation.