![]() Therefore it is clear that Mercury fluid will correspond with this fluid. Solution: First calculate the dynamic viscosity using the following formula, using the given values, Mercury with dynamic viscosity 1.526 \(Pa\ s\) Water with dynamic viscosity 1 \(Pa\ s\)Īir with dynamic viscosity 0.018 \(Pa\ s\) According to its dynamic viscosity, to which one of these fluids corresponds? Q.1: A fluid with a shear rate of 0.5 per second, and the shearing stress 0.76 N per m². We measure Dynamic viscosity in the unit of Pascal second or \(Pa\ s\) Solved Examples In the form of the equation, we can write it as: Thus, we can express it as:ĭynamic viscosity = \(\frac \) Since dynamic viscosity is the tangential force required to move one horizontal plane of a fluid with respect to another. Dry air: 113 293373 Helium: 72.9 Air - Dynamic and Kinematic Viscosity - The Engineering ToolBox Thermophysical Properties of Fluid Systems - NIST Chemistry. Viscosity is determined by measuring the force i.e. These instruments will rotate a probe in the liquid sample. The rotational viscometer is a popular instrument, used to measure the dynamic viscosity. Thus dynamic viscosity can be expressed as the tangential force per unit area required to move the fluid in one horizontal plane with respect to another plane, with a velocity of unit value while the fluid’s molecules maintain a unit distance apart. Therefore, the dynamic viscosity is the force needed by a fluid to overcome its own internal molecular friction so that the fluid can flow. The viscosity acts as an important fluid property during the analysis of liquid behavior and fluid motion near solid boundaries. This is a kind of tangential force that acts when one horizontal plane moves with another one. Shear stress in the fluid is possible due to the intermolecular friction exerted when layers of fluids attempt to slide over each other.ĭynamic Viscosity Formula for the fluid will define its internal resistance to flow due to some shearing force. Also, the way it will move when it comes in contact with solid boundaries.Ī fluid’s viscosity is the measure of the resistance to its gradual deformation by tensile or shear stress. Viscosity is an important property of the fluid material and is useful to understand the fluid’s behavior. One way is to measure a fluid’s resistance to flow when an external force is applied and is the dynamic viscosity. It is not easy to find a lot of information on the differences between dynamic and kinematic viscosity. please help.2 Solved Examples Dynamic Viscosity Formula What is Dynamic Viscosity? There are a lots of equations to find Nu, but not sure which one to use. the material used for the tubes is stainless steel and thermal conductivity is k = 17W/m✬. the velocity of air just before it reaches the staggered tubes is u∞=37.8m/s and the mass flow rate of water just before it reaches the tubes is 0.23kg/s. Outside the tube air is used and at the entrance the temp is 293K and at exit is 318K. Hot water is passing trough the tube, at an entrance temp of 393K and exit of 303K. each tube is 76.2mm and for every 5mm of the tube there is 5 fins at a width of 0.5mm( see picture). The base area which the fines are attached to the tubes is 0.5mm x 0.5mm and the length of the fins depends on the spacing between the tubes. All the measurements shown in the attachment are in mm. Each tube will have 6 fins attached to it, which will connect all the tubes together, see figure2(only half the lenghts of the fins are shown here). These tubes are to be connected with fins. ![]() The picture below shows the dimensions of the tubes and the spacing between them. i am getting confused with the minimmum flow area to which equation to use. Since these are the default values, no change is required in the Create/Edit Materials dialog box. For the present analysis, you will model air as an incompressible fluid with a density of 1.225 kg/m and a dynamic viscosity of 1.7894 10 kg/m-s. i am suppose to find the heat transfer and thus working out the fin effectivness and the efficiency. ANSYS FLUENT 12.0 Tutorial Guide - Step 4: Materials. the measurments of the fins and tubes are given in the attachement. the tubes are connected to each other with fins. I have got a staggered tube arrangment, and has and arrangment of 15rows x 15tubes. Hey, i am stuck on a heat transfer related question for the last few weeks.i am not sure how to approch the problem. ![]()
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