International CAE Conference: Agenda. Other Authors. Roberta Messina, Tecnohit | Fabio Zanoletti, Tecnohit. Abstract. INTRODUCTION In recent years and thanks to cloud computing development, a certain number of companies are proposing tools to simulate directly from your own browser using remote hardware resources. In many cases, these tools are user- interfaces that allows an easy management of open- source software such as Open. FOAM. As one may expect, given the popularity of both CFX and Open. FOAM, many comparisons already exists such as [1], [2] and [3]. Beside this, given the high number of users of Open. FOAM there are comparisons between Open. FOAM with experimental results, such as [4]. In the abovementioned tools, the presence of a user- interface actually limits the choices available in standard Open. Fig. 4.1. a Open-pit mine in Central Massif (France): an underground ore 3D model points out unknown mineralization which extended the mine life by more than 10 years. International CAE Conference and Exhibition: numerical simulation techniques. Top VIdeos. Warning: Invalid argument supplied for foreach() in /srv/users/serverpilot/apps/jujaitaly/public/index.php on line 447. FOAM in terms of boundary conditions and numerical schemes in particular, rising a new need of results validation for these modern tools. SOFTWARE The software used for the current comparison are ANSYS CFX v. CONSELF v. 2. 9. 2, one of the abovementioned cloud providers based on CFD solver Open. FOAM v. 4. 1. GEOMETRY AND MESH The geometry considered is a simple bulb valve where pressure drop calculation is the main simulation drive. Given the geometry in STEP format two different meshes have been defined for the two solvers. With the possibilities offered by both systems, parameters were chosen in order to produce a similar quality mesh in both cases. A tetrahedral meshing algorithm has been chosen, with boundary layer treatment in both cases (5 layers with a first wall height of 8. E- 4 m) calculated to maintain y+ in the acceptable range for the used turbulence model. Mesh surface dimension is 2. E- 3 m, resulting in about 1 million elements in both configurations. CFD ANALYSIS The CFD analysis is an incompressible steady flow at Re ⋍ 1. Four different boundaries are applied according to the following scheme: velocity inlet, pressure outlet, symmetry and wall. Turbulence is taken into account using a standard k- ε model [5]. In order to reduce as much as possible the boundaries effects on the valve results, inlet and outlet boundaries are placed at least 5 times farther than dh - hydraulic diameter. NUMERICAL SCHEMES The main difference between the two simulation software used is the numerical schemes used. CONSELF, based on Open. FOAM, can be described as a collocated software where variables are solved in segregated way with a SIMPLE pressure- velocity coupling is implemented [6]. From the numerical point of view, gradient reconstruction is computed using a linear Gauss hypothesis, whilst the convective schemes uses a second order linear- upwind scheme, bounded to improve stability. Viscosity flows are limited, for the sake of stability, not to exceed the orthogonal contribution. From the algebraic point of view, two solvers are used: algebraic multi- grid for the continuity equation and Gauss- Seidel for all the other variables. CFX is a pressure- velocity coupled software. The reconstruction of the gradient term is computed using finite- element- shape functions. The convective term is computed using the High- Resolution- Scheme [7], that is a bounded scheme. As said before, the main global result to be considered in the simulation is the pressure drop, calculated as the difference of static pressure at the inlet and at the outlet. Given this global parameter, further investigation on local variables are considered, such as pressure and velocity across the valve. ANSYS CFX | CONSELF OPENFOAM - 9. EXTRA CONTENTS IN FINAL PAPER The final paper is going to provide further details beside those here reported. A more advanced mesh comparison (also in terms of mesh quality, skewness and orthogonality) is necessary to provide a general overview of the results. Extra results post- processing will be provided in terms of graph comparisons, extracting velocity profiles at different locations.
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