Abstract
Fast and accurate computation of thermo-physical properties is essential in computationally expensive simulations involving fluid flows that significantly depart from the ideal gas or ideal liquid behavior. A look-up table algorithm based on unstructured grids is proposed and applied to non-ideal compressible fluid dynamics simulations. The algorithm grants the possibility of a fully automated generation of the tabulated thermodynamic region for any boundary and to use mesh refinement. Results show that the proposed algorithm leads to a computational cost reduction up to one order of magnitude, while retaining the same accuracy level compared to simulations based on more complex equation of state. Furthermore, a comparison of the LuT algorithm with a uniformly spaced quadrilateral tabulation method resulted in similar performance and accuracy.
Highlights
The accurate estimation of thermo-physical properties of fluids is essential for many engineering and scientific applications, and it requires complex models in case the behavior of the fluid departs from that of the ideal gas or ideal liquid
Fluid dynamic simulations of vapors in non-ideal states are employed in more fundamental research and the branch of fluid mechanics dealing with this type of fluid flows was recently termed non-ideal compressible fluid dynamics (NICFD) [6]
In order to assess the performance of the method, the computational cost of the nozzle simulation relying on the ug-LUT algorithm for the evaluation of fluid properties is compared with one in which the properties are provided to the flow solver by the external thermodynamic library based on the Span-Wagner equations of state (EoS) (SWsim), for an increasing number of thermodynamic mesh nodes
Summary
The accurate estimation of thermo-physical properties of fluids is essential for many engineering and scientific applications, and it requires complex models in case the behavior of the fluid departs from that of the ideal gas or ideal liquid. [1,2,3,4] In these cases, the evaluation of thermo-physical properties is often necessary for system design and performance evaluation or to simulate the flow behavior within components. The computational cost associated with fluid thermodynamic models expressed in terms of equations of state (EoS) can become a limiting factor if accurate estimations are needed in combination with expensive simulations. This is the case, e.g., in the design and optimization of industrial components [7] or in computational. In order to decrease the computational time related to the calculation of thermo-physical fluid properties, while maintaining a satisfactory level of accuracy, look-up table (LuT) methods are convenient and widely adopted [9]
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