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Flow past a circular cylinder located between free-surface and wall boundaries is modelled numerically using non-uniform particle size incompressible smoothed particle hydrodynamics (SPH).Several enhancements including Rhie and Chow interpolation, colour function-based free surface tracking, and modified particle shifting are introduced to increase the accuracy and efficiency of the method. A parameter study at constant Reynolds number, Re = 150, examines the influence of Froude number (Fr = 0.2 − 0.6), submergence ratio (H/D = 0.5 − 1.0, where H is the distance between the apex of the cylinder and undisturbed free surface, and D is the cylinder diameter), and bottom gap ratio (G/D = 1.0−5.0, where G is the distance between the base of the cylinder and the bed) on the ambient free-surface flow pattern and hydrodynamic force on the cylinder. It is found that the vortex shedding pattern depends on all three parameters. As the Froude number increases for fixed submergence ratio and bottom gap ratio, vortex shedding is eventually suppressed. As the

Industrial clusters contributed significantly to the spread of Covid-19 worldwide, including in Indonesia. One of the causes is that maintaining a minimum distance of 1 to 2 meters between workers is often challenging due to the plant layout and work system design limitations. Therefore, an intervention to the workstation is needed to protect industrial workers from potential exposure to Covid-19 and other airborne infections. One technology that has a high potential to be applied to solve this problem is the air curtain/personalized ventilation. This research analyzes the effectiveness of downward push-pull air curtain in protecting workers from inhaling the infected microdroplet. The extent to which the downward push-pull ventilation can withstand the burst of microdroplets was studied by varying the air speed ratios of the air curtain. A 2D simulation was carried out with Salome, OpenFOAM, and ParaView softwares. Two scenarios were tested, i.e., the distance between the person who is coughing is 0,5 and 1 meter from the air curtain. For the distance of 0,5 meter, the results showed that the optimum velocity ratio between the pushed and pulled air was 0,17 with a droplet penetration percentage of 8,98 %. While for 1 m, the optimum velocity ratio was 0,25 with a droplet penetration percentage of 5,67 %.

This work, fluid flow and heat transfer in single and multi phase flow chould be enhanced by turbulent flow in heat exchanger tube with one of heat transfer augmentation techniques. Characteristic of globular tube fitted with the multiple conical strips insert were investigated. Most of study are related with this work, they found that an addition by single conical strips insert will make nusselt number increase 5%. Unfortunately, it was also increase pressure drop about 10%. This work improve their work by adding amount of conical strips inserts.The modification that will become 4 variation number of conical (n = 2, 3, 4, and 5) with 4 kind of central angle ( = 20 o , 30 o , 40 o , and 50 o ), it is shown that the best performance of conical strips insert configuration is 2 peace of strips with 20 o central angle. This work successfull improve Performance heat transfer value in tube about 11% compare with A. Fan et al work. Thus achieve a high overall heat trasnfer performence and it is a promising tube insert which would be widely used in heat transfer process turbulent flow.

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