Труды Института системного программирования РАН (Oct 2018)
Calculations of continouosly stratified fluid flows using the open source computational packages on basis of the technological platform UniHUB.
Abstract
The paper presents the authors' experience in usage of the technological platform UniHUB for numerical simulation and computations of continuously stratified fluid flows based on the open source computational packages OpenFOAM, Salome and ParaView. Special attention is paid to the problems of high-resolution computational grids construction, complex boundary conditions setting using the standard and extended OpenFOAM utilities, own solvers development, numerical data processing and visualization and running program codes in parallel on the JSCC RAS Cluster, as well. Some physical results are demonstrated on the stratified flows structure and dynamics around impermeable sloping plate, symmetrical wedge, horizontal disc and circular cylinder. The obtained numerical results have direct application to the natural systems since the Earth’s atmosphere and hydrosphere are mostly stably stratified due to non-uniformity of distributions in space and time of dissolved or suspended matters, gas bubbles, temperature, medium compressibility and effects of external forces. The numerical study of diffusion-induced flows on an impermeable obstacle reveals a system of jet-like flows formed along its sloping boundaries and a complicated structure of circulation cells attached to the surface of the obstacle. The most intensive structures are clearly registered experimentally by Schlieren techniques in form of horizontally extended high gradient interfaces attached to extreme points of an obstacle, i.e. sharp edges of a plate, poles of a cylinder, vertices of a wedge, etc. With increase of typical velocities these structures do not disappear but are transformed into a complicated system of thin interfaces separating different kinds of disturbances, e.g. internal waves and a vortex sheet. The structural elements of extremely slow flows of non-homogeneous fluids form a flow fine structure in rapidly changing environments. The analytical, numerical and laboratory data are compared with each other, conditions of their agreement being discussed together with possibility of their application to the natural systems.
