Inlet Pressure Cancellation for Fluid Simulation Accuracy
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Solution Overview
Problem
Existing digital simulation methods for airflow over vehicles, such as LES and DNS, often introduce undesired acoustic pressure waves due to numerically generated turbulence, which are not present in physical environments, leading to inaccurate simulations.
Innovation Solution
A computer-implemented method that iteratively measures and subtracts numerically generated pressure waves from the applied inlet boundary pressure to establish corrected boundary conditions, reducing undesired pressure waves to a threshold value, thereby improving the accuracy of fluid simulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If upstream turbulence is introduced to better represent in-service flow conditions, then the realism of flow conditions is improved, but undesired acoustic pressure waves are generated that are not present in the physical environment
Solution Approach 1:
The patent performs a preliminary simulation to identify and characterize the acoustic pressure waves generated by turbulence generation methods before using those methods in production simulations. This preliminary action allows the harmful waves to be measured and stored for subsequent cancellation, resolving the contradiction by preparing the cancellation data in advance.
Solution Approach 2:
The patent applies preliminary anti-action by generating cancellation boundary conditions that are equal in magnitude but opposite in sign to the measured acoustic pressure waves. These anti-waves are applied at the inlet boundary to preemptively cancel the harmful acoustic waves before they can contaminate the production simulation results.
2Measurement precision
If iterative pressure cancellation is performed to reduce numerically generated pressure waves, then simulation accuracy is improved, but computational time and iterations are increased
Solution Approach 1:
The patent implements feedback by measuring the acoustic pressure waves generated during preliminary simulations and using those measurements to construct cancellation boundary conditions. The measured pressure history from preliminary runs feeds into the production simulations, creating a closed-loop system where the output of one simulation improves the accuracy of the next.
Solution Approach 2:
The patent applies partial action by performing pressure cancellation only at the inlet boundary where the acoustic waves are generated, rather than attempting to cancel waves throughout the entire computational domain. This localized approach reduces the computational overhead while still achieving significant accuracy improvement.
Data Source
AI summary
Disclosed are computer implemented techniques for correcting for numerically generated pressure waves at an inlet of a simulation space. The techniques include receiving a model of a simulation space and applying an inlet pressure to an inlet of the simulation space. The applied inlet pressure generates fluctuating velocities that produce undesired, numerically-generated pressure waves. The numerically generated pressure waves are measured to establish a measured pressure history. The measured pressure history is subtracted from the applied inlet boundary pressure history to provide a set of boundary conditions. The process conducts a fluid simulation using the set of boundary conditions. The process repeats using a subsequent set of boundary conditions, until an iteration is reached where the measured pressures near the inlet are sufficiently small to compensate for undesired, numerically-generated pressure waves, and thereafter stores that subsequent set of boundary conditions to provide a corrected set of boundary conditions.