Computational Grid Reform for Moving Boundary Fluid Dynamics
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Solution Overview
Problem
Existing computer modeling methods for fluid dynamic systems struggle to accurately handle moving boundaries in multi-cell models, particularly in transient conditions, as they fail to properly transport thermophysical properties across moving surfaces, leading to inconsistencies and inaccuracies in simulations.
Innovation Solution
A method and apparatus that identify cells adjacent to the moving surface, compute effective thermophysical value fluxes based on the surface's movement, solve transport equations to determine updated cell values, and reform the grid to comply with the moving surface, ensuring conservation of quantities across boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional multi-cell modeling methods are used for moving boundaries, then the geometric grid structure remains simple and fixed, but the transport of thermophysical properties across moving surfaces becomes inaccurate
Solution Approach 1:
The patent applies the dynamics principle by allowing the computational grid to dynamically adapt to moving boundaries through a cut-cell approach. The grid cells are dynamically cut and reconfigured at each time step to conform to the moving surface position, enabling accurate tracking of thermophysical properties across transient boundaries while maintaining a fixed underlying grid structure.
Solution Approach 2:
The patent segments the computational domain into multiple cells with moving boundaries represented as cut-cells. By dividing the domain into discrete cells and independently handling the boundary-cutting operation for each cell, the method achieves accurate property transport while keeping the overall grid structure manageable and computationally efficient.
2Manufacturing precision
If the grid is reformed to comply with the moving surface at each time step, then the accuracy of boundary representation is improved, but the computational cost increases
Solution Approach 1:
The patent applies partial action by reforming the grid only in the regions affected by moving boundaries (cut-cells) rather than reconfiguring the entire computational grid. This localized approach maintains boundary accuracy where needed while preserving computational efficiency in regions unaffected by boundary motion.
Solution Approach 2:
The patent performs preliminary identification of cells adjacent to the moving surface at the beginning of each transient time step. By pre-identifying which cells will be affected by boundary motion and preparing the cut-cell configuration in advance, the method optimizes the computational workflow and reduces overall computational cost.
3Reliability
If thermophysical properties are transported across moving boundaries using fixed grid methods, then the computational algorithm remains simple, but conservation of quantities across boundaries is violated
Solution Approach 1:
The patent changes the computational parameters by computing effective thermophysical value fluxes that account for the relative motion between the fixed grid and moving boundaries. This involves modifying the flux calculation to include boundary velocity effects, ensuring that mass, momentum, and energy are conserved across moving surfaces while maintaining a relatively simple algorithmic framework.
Data Source
AI summary
Method for treating a moving surface during a transient condition in a computational fluid dynamics system multi-cell computer model, the model having a fixed underlying geometric grid, includes identifying cells in the grid adjacent the moving surface at the beginning of a transient time step and identifying beginning adjacent cell boundaries formed in the grid by the moving surface. The method also includes computing effective thermophysical value fluxes through the beginning cell boundaries in accordance with the sense of the movement of the moving surface relative to the beginning adjacent cells. The method further includes solving transport equations for all the cells to determine cell thermophysical values at the end of the time step, using the computed effective fluxes and reforming the grid to comply with the moving surface at the end of the time step. Apparatus includes a digital computer programmed to carry out the above method.