Table of Contents
What is grid sensitivity test?
Grid Sensitivity refers to all CFD computations not only turbomachines.No solution should be accepted unless it is grid independent. This means that a computer run is repeated with finer and finer grids until the results at all points in space do not change anymore.
How do you do the grid independence test fluently?
Just start with a coarse grid (let’s say 50 points spanwise) and refine the mesh in all directions (both normal to the wing and spanwise/chordwise) until results stop differing between the solutions (or at least differ <2\%). Then you can call your solution grid independent.
What is grid convergence test?
The method involves performing the simulation on two or more successively finer grids. The term grid convergence study is equivalent to the commonly used term grid refinement study. Methods for examining the spatial and temporal convergence of CFD simulations are presented in the book by Roache.
What is a grid independent solution?
Grid-independent means calculational results change so little along with a denser or looser grid that the truncation error can be ignored in numerical simulation. If the results tend towards identical, the grid can be considered as grid-independent.
What is Grid Convergence Index?
The Grid Convergence Index – GCI (Roache, 1994) is a method to estimate the discretization error even when the successive mesh refinements are not integer multiples. This technique is defined as an error percentage, providing a confidence bound in which the numerical solution will likely to be.
What is grid dependency?
Grid dependency test ia a method used in FEA to get the optimum results by reducing mesh density in a given component. Mesh refinement, mesh convergence are the other names used to define Grid dependency test.
What is grid refinement study?
Grid refinement study is performed for the Dethridge water wheel model on three different grid resolutions and numerical uncertainty is quantified using the Grid Convergence Index (GCI). Key parameters relevant to the wheel performance are analysed and compared with the measured values.
What is a grid refinement study?
Grid refinement study is performed for 3D CFD model with rotating object. • Numerical uncertainty of CFD model of the Dethridge wheel is quantified using GCI. • Assessing uncertainty on 3D model with moving object is computationally intensive.
What is grid resolution?
Resolution is defined as the minimum distance between two objects that can be separated in the image. Many people mistakenly equate “resolution” to “pixel” or grid cell size, when resolution is actually approximately 2.83 times grid cell size.
How do you study for mesh independence?
What is a Mesh Independence Study?
- Isolate an area of interest on the geometry. If the model is small, this could be the whole geometry.
- Determine a method to quantify the nodes on the area of interest.
- Refine the mesh in the are of interest.
- Choose a result to study.
- Compare the results for the various runs.