Impacts of the laminar airflow ventilation system design factors on contaminant removal and thermal comfort condition in an operating room have been investigated by means of Lagrangian-based particle transport using the non-Boussinesq modeling of the buoyancy effects. An operating room including staffs and a patient with realistic human geometries and two surgery lights are included in simulations. The laminar airflow system is placed on the ceiling with a surrounding fixed-height partial wall and the air barrier supply grills. Effects of density change in mixed convection flow regime are included by the non-Boussinesq modeling of the exact air density variation. The predicted mean vote, the age of air, the colony-forming units per cubic meter, the average temperature, the average velocity, the relative humidity, the density distribution, and the positions of particles are calculated to assess the indoor air ventilation quality. A total of 27 simulation cases have been considered to determine the impact of three main design factors including the laminar airflow system area, the supply air, and the air barrier velocities on the performance of the system. It is concluded that for the curtain velocity of 2 m/s, the thermal comfort reduces with increasing the laminar airflow velocity, but for the third staff, the results show that for small laminar airflow areas, the speed of the inlet port should be reduced and for the larger sizes, the inverse of this trend is recommended. Moreover, for all cases the humidity varies within the range of 55%–56%, which agrees well with the suggested standard humidity range between 50% and 60%. It is concluded that the cases of the laminar airflow velocity equal to 0.3 and 0.5 at the curtain velocity of 1 m/s are generally more appropriate than other cases due to less accommodation of particles near the entire body of the patient.

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The energy released during the bubble collapse process is used for medical and industrial purposes. The present study investigates the effects of electrohydrodynamic force on the collapse phenomenon near the rigid wall and the enhancement of the collapse energy. A solver in the OpenFoam open-source code is developed based on the volume-of-fluid model, in which the effects of compressibility, energy transfer, and electrohydrodynamic force are included. The developed solver is validated against the available experimental data, and a good agreement is seen. The effects of an electric field on the bubble collapse for the range of the electrocapillary number (CaE) of 0–5.76 and normalized wall distance (γ) of 0.8–2.0 are investigated. The results indicate that the bubble is deformed due to the presence of an electric field, and the values obtained for the maximum velocity and pressure are 33 and 35 times the state without the electric field at γ = 2 and CaE = 5.76, respectively. Also, due to the increase in velocity, the maximum shear stress on the rigid wall is increased up to seven times in the absence of the electric field. Therefore, the jet force obtained from the bubble collapse can be enhanced by applying the electric field in the continuous phase fluid. Also, the correlations are proposed to estimate the jet velocity, pressure, and wall shear stress of bubble collapse in the presence of an electric field.

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