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CHERNICA, Ion. Calculation of resistance force at incompressible viscous fluids laminar motion. In: Materials Science and Condensed Matter Physics. Ediția a 9-a, 25-28 septembrie 2018, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2018, p. 259.
|Materials Science and Condensed Matter Physics
Ediția a 9-a, 2018
Conferința "International Conference on Materials Science and Condensed Matter Physics" |
Chișinău, Moldova, 25-28 septembrie 2018
In the nearly two hundred years of research in the field of viscous fluid dynamics, various methods of calculating viscosity have been proposed. Most of them are based on tensor calculus and only in singular cases relations based on the principles of general physics have been obtained, using the first impulse theorem – the quantity of motion theorem [1, 2]. The development of a simple method of calculating the strength of laminar motion resistance of incompressible fluids can therefore be regarded as one of the priority problems of modern hydrodynamics. For the calculation of the strength of the laminar motion resistance of the incompressible viscous fluids, we apply Newton's viscous law to a fluid particle of the shape of an elementary parallelepiped of dimensions For the begining, examine the unidirectional motion along the OX axis (fig. 1). Considering tangential tension linear with the length, the frictional force exerted between two neighboring layers, spaced apart from each other. According to Newton's viscous friction law, the tangential frictional tension between two neighboring layers of the unidirectional viscous fluid is directly proportional to the linear variation of the velocity in the transverse direction to the general direction of motion, meaning . In the hypothesis of the constant of the coefficient of dynamic viscosity for the resistance force that is exerted in the XOZ plane it is obtained Similar are the expressions of the resistance forces caused by the variation in the amount of motion in the other two planes. The resistance force a mass unit exerted on the OX direction. .