Microclimate-UMCF Project Documentation

This document provides a comprehensive overview of the VIP-SMUR Spring 25 - Microclimate-UMCF project, which focuses on simulating and analyzing microclimate effects, particularly those involving vegetation and building materials.

Project Goals

The overarching goals of this project are:

• To simulate various microclimate scenarios using computational fluid dynamics (CFD) tools such as OpenFOAM's urbanMicroclimateFoam solver and explore alternative tools like ENVI-met.
• To understand how different parameters, including vegetation properties (like leaf area index, tree types, and root systems) and building material characteristics, influence microclimate conditions like temperature, humidity, and wind flow.
• To validate simulation results against established benchmarks, such as the HAMSTAD benchmarks, and to refine simulation methodologies.

Key Research Areas

Vegetation Effects on Temperature

• Sensitivity Analysis: Determining how sensitive temperature changes are to variations in vegetation parameters like Leaf Area Index (LAI), tree species, and root system characteristics.
• Experimental Design: Developing a series of simulation experiments to isolate and study the impacts of key vegetation variables.
• Simulation and Iteration: Conducting simulations, analyzing results, and iteratively refining models to identify the most influential vegetation factors.

Building Materials

• Solver Research: Reviewing solver documentation (wikis) and published research to understand how building materials are modeled and implemented.
• Case Study Formulation: Developing relevant case studies, possibly based on the Georgia Tech campus or other real-world projects, to test the effects of different building materials.
• Simulation Runs: Conducting simulations to observe and quantify the impact of various building materials on the surrounding microclimate.

Technical Implementation and Challenges

• Terrain Modeling: Implementing terrain features in the UMCF (Urban Microclimate CFD) model, including the creation of terrain patches and handling underground cells.
• Grass Geometry: Integrating grass geometry into the simulation domain.
• Solver Exploration: Investigating the hamFoam solver, including its governing equations, assumptions, and wiki documentation.
• Error Handling: Addressing and resolving various warnings and errors encountered during simulations, such as FaceWarning messages.
• Mesh Generation: Optimizing mesh creation processes to reduce computational time and improve accuracy.

Progress and Weekly Updates

The project progressed through several phases, documented by weekly updates, including:

• Weeks 1/27 & 2/6: Initial setup, parameter sensitivity analysis, and implementation of Foamonary and Foamist.
• Weeks 2/13 & 2/20: Implementing terrain features, creating terrain patches, and addressing boundary condition issues, particularly with mappedWall.
• Weeks 2/27 & 03/06: Continued troubleshooting with ENVI-met and revisiting its use for comparison. Refinement of terrain parsing and processing.
• Weeks 03/13 & 03/31: Facing slow simulation speeds with ENVI-met, encountering timestep errors in OpenFOAM, and working with viewFactorsGen.
• Week 04/07 & After Break: Analyzing simulation results, varying wind parameters, and attempting to probe points for data collection.

Detailed Technical Issues and Solutions

FaceWarning Messages

• Encountering FaceWarning messages during mesh creation.
• Investigating the relevance of these warnings and their potential impact on simulation accuracy.
• Exploring methods to optimize mesh creation and reduce/eliminate these warnings.

Boundary Condition Issues

• Troubleshooting issues with the mappedWall boundary condition.
• Ensuring correct face mapping between building geometries and the air region.
• Resolving discrepancies in the number of faces between different regions.

Solver Errors

• Debugging crashes of urbanMicroclimateFoam due to timestep issues.
• Addressing FOAM FATAL ERROR related to dynamic list capacity in viewFactorsGen.

ENVI-met Challenges

• Encountering difficulties saving SIMX files in ENVI-met.
• Experiencing slow simulation speeds and limitations in the trial version.
• Issues with remote desktop access and administrator permissions.

Benchmarking and Validation

• HAMSTAD Benchmarks: Utilizing the HAMSTAD benchmarks to compare simulation results and validate model accuracy.
• ETH Zurich Resources: Accessing and utilizing benchmark descriptions, input data, and result data from ETH Zurich's Gitlab repository.

Simulation Parameters and Analysis

• Wind Conditions: Varying wind speed and direction to observe their impact on temperature, humidity, and CO2 levels.
• Temperature and Humidity: Analyzing the spatial distribution and variation of temperature and humidity within the simulation domain.
• CO2 Levels: Investigating CO2 concentration at different heights.
• Probing Points: Attempting to probe specific points within the brick blocks to collect detailed data.

Tools and Software Used

• OpenFOAM: Primary CFD software used, particularly the urbanMicroclimateFoam and hamFoam solvers.
• ENVI-met: Explored for comparative analysis but faced several challenges.
• Rhino: Potential use for 3D modeling and geometry preparation.
• WSL (Windows Subsystem for Linux): Used to run simulations on an Ubuntu 20.04 environment.
• blueCFD-Core-2020: Specific distribution of OpenFOAM used for the project.

Current Status

The project involves ongoing efforts to refine simulations, troubleshoot persistent issues, and validate results against established benchmarks. Continued work on ENVI-met and debugging specific solver errors is in progress.

Presentation

Team