The chaotic situation of Aleppo in the fifth century AH on the one hand, and the loose domination of the Fā timī ds in this city on the other hand led to the formation of a self-governing and militia force in the city. The group that took over Aleppo’ s administration came to be known as "EHDā th. " The power of this group, which had the city under its control, was directly linked to local governments in the region, as the weak governance and exiting gaps reinforced their rule. However, with the dominance of the Seljukite, and then the rule of the Ortoghiā n and the Zangiā n over Damascus, the power of EHDā th began to decline in the wake of their policy of constant changing of city officials and appointment of people from outside of Aleppo.

The electrohydrodynamic (EHD) drying of Poly (vinyl acetate) latex films was experimentally investigated in a wind tunnel. The influence of various conditions such as the air temperature, air velocity, and concentration of the latex solution, in the presence and the absence of a high electric field, was investigated. The effects of the applied voltage intensity, electrode gap, number of needle electrodes, and polarity of corona on the drying rate of polymer films were studies. The drying behavior of films in a wind tunnel was observed by the weighting method and analyzed based on the heat and mass transfer. Results showed the importance of the EHD role in the drying rate of the polymer film. Increasing the intensity of the electric field, number, and configuration of needle electrodes, and decreasing the electrode gap lead to a significant enhancement of the drying rate of the polymer film. Scanning electron microscope (SEM) images were used to analyze the effect of EHD on the morphology of dried films.

In the present research, the effects of an electrohydrodynamic actuator on the flow around circular cylinder have been investigated numerically using the finite element method by Ansys software. For this purpose, after selecting proper domain and suitable boundary conditions, at first electric field has been analyzed numerically and then their results have been introduced to the governing equations of fluid field as electrical body forces. In this way, the influence of ionic wind resulted from the electrohydrodynamic actuator on the fluid velocity, fluid pressure, extended wake behind circular cylinder and also drag coefficient of the cylinder has been resolved. According to the results, the fluid flow near of wall of frontal surface was accelerated. For the actual arrangement of the electrodes, the pressure difference between the frontal and back of the cylinder was increased and caused the enhancement of drag force. But on the other hand, according to the results, this phenomenon causes the diminution of the wake region on the cylinder.

Electrohydrodynamic Fe3O4-Ethylene glycol nanofluid forced convection is simulated in existence of thermal radiation. The porous lid driven cavity has one moving positive electrode. Single phase model has been applied to simulate nanofluid behavior. Control Volume based Finite Element Method is employed to obtain the results which are the roles of Darcy number, radiation parameter, Reynolds number, nanofluid volume fraction and supplied voltage. Results depict that maximum values for temperature gradient is obtained for platelet shape nanoparticles. Nusselt number enhances with rise of Darcy number and supplied voltage. Convection mode enhances with increase of permeability of porous media and nanofluid volume fraction but it decreases with rise of Hartmann number.

One of the ways, to control of the drag forces applying to the circular cylinder in the air flow, is control of the generated boundary layer around the cylinder, and one of the new and effective ways for control of the boundary layer, is using high voltage electrostatic field in fluid flow. In these conditions, because of the coupled relations between electric field and momentum equations, the problem is complicated and discussed as electro-hydro-dynamic or EHD. For this purpose, the equation of conservation and momentum for flow field and conservation for electric density and Poisson's for electric field are solved with numerical and finite element method. In this research we used two wire and two plate electrode for generation electric field. By use of the results, we observed that the effect of electric field on fluid flow field is widely dependent on geometry of the electrodes and the intensity of the electric field. But in fact, by applying these forces, particles momentum and the velocity of them is increased. It was shown that increasing in Reynolds number, decrease these effects.

Experimental investigation on heat transfer enhancement by applying electrohydrodynamics (EHD) in partially open multiple fined enclosures with different aperture position has been performed. The enclosure had five thermally and electrically insulated faces; while one face was copper finned plate with an aperture located on its opposite face. In the present study, different parameters including electric current, number of fins, aperture position, and corona polarity were investigated. It was concluded that heat transfer enhancement is proportional to the supplied current. Higher number of fins can lead to further heat transfer enhancement and as the location of aperture is shifted upward, the heat transfer coefficient is improved more significantly by EHD.

The dried products quality is influenced by the drying methods and different temperatures, especially on their smell and aroma. The electrohydrodynamic (EHD) method as a non-thermal drying method has an increasing effect on the rate of evaporation of product moisture content in ambient temperature and pressure, and preserve quality in dried food products. The objective of this study was to classify the quality of dried dates at three different air velocity by different drying conditions of electrohydrodynamic (EHD in 25 and 35 ° C), hot air (HA at 60 ° C) and hybrid drying (EHD-HA at 60 ° C) techniques based on odor using a multi-sensory olfactory machine. The results showed that dried date fruit quality base on its odor was classified to three classes (1: EHD at 25° C, 2: EHD at 35° C and 3: HA and EHD-HA at 60 ° C). The response of metal oxide semiconductor sensors in EHD method at 25 ° C was higher than the others which show the aroma of dried date fruit in class 1 is conserved more better than the other classes. Finally, the effective sensors were determined to recognize the odor of date fruit.

In this paper, effects of EHD actuators on hydrodynamic behavior and heat transfer of air flow over a circular cylinder were considered. Pressure and temperature distributions around the cylinder were measured in presence of wire-plate EHD actuators. The Reynolds number based on cylinder diameter (d) were 3500, 7000.Experiments were performed for various configurations. Based on obtained results, the flow field around the cylinder was affected significantly by EHD actuation. The flow visualization confirmed the formation of separation bubble because of EHD actuation and affected pressure distribution dramatically. Measured temperatures showed that the excess flow, resulted from corona wind, enhanced local and average heat transfer over the cylinder.