1D CFD Model Correction for Multiphase Slug Flow
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Solution Overview
Problem
Current one-dimensional (1D) CFD models struggle to accurately predict Taylor bubble velocities in multiphase flows, leading to inaccuracies in slug flow predictions, which are crucial for designing and operating pipeline transport systems, as they fail to capture three-dimensional mechanisms inherent in Taylor bubble velocity.
Innovation Solution
A computer-implemented method is introduced that forces the 1D CFD model to predict Taylor bubble velocity by adding a force term to the gas momentum equation, proportional to the difference between the predicted and predetermined Taylor bubble velocity, and applies a similar correction to the liquid phase, ensuring momentum preservation and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a 1D CFD model is used to simulate multiphase flow in pipelines, then computational efficiency and simulation speed are improved, but prediction accuracy of Taylor bubble velocity and slug flow characteristics deteriorates
Solution Approach 1:
The patent introduces an intermediary correction term in the momentum equation that mediates between the simplified 1D model and the more accurate 3D physics. This correction term, based on the difference between predicted and predetermined Taylor bubble velocities, allows the 1D model to incorporate 3D effects without requiring full 3D computational complexity, thus maintaining both speed and accuracy
Solution Approach 2:
The patent modifies the momentum equation parameters by adding a correction term that changes the velocity prediction behavior. By adjusting this parameter based on the difference between model predictions and predetermined velocities, the system transforms the 1D model's accuracy without changing its fundamental computational structure or dimensionality
2Device complexity
If the 1D CFD model uses standard momentum equations without correction terms, then model simplicity and ease of implementation are maintained, but accuracy in capturing three-dimensional mechanisms is lost
Solution Approach 1:
The correction term is applied locally at specific locations within the pipeline model, particularly at the Taylor bubble tail where it most significantly impacts slug flow characteristics. This localized application maintains model simplicity in most regions while improving reliability where it matters most
Solution Approach 2:
The correction approach treats the gas and liquid phases asymmetrically by applying the velocity correction primarily to the gas phase momentum equation, recognizing that Taylor bubbles (gas phase) are the primary source of prediction errors in 1D models. This asymmetric treatment improves reliability without requiring symmetric complexity changes across all equations
Data Source
AI summary
This invention relates to a computer-implemented method for predicting fluid behaviour in pipeline-based transport systems for transport of multiphase flows involving slug flows which forces one-dimensional CFD models to predict a Taylor bubble velocity being equal to a predetermined Taylor bubble velocity known to be realistic. The enforcement of the 1D CFD model to arrive at the predetermined Taylor bubble velocity is obtained by introducing a force term in the momentum equation for the gas phase at and near the slug-tail top and which is proportional to the difference between the Taylor bubble velocity predicted by the CFD model and the predetermined Taylor bubble velocity. The invention further relates to an autonomous system applying the computer-implemented method.