HAD Simülasyonlarında Ağ Yakınsama İndeksi ve Richardson Ektrapolasyonun Uygulaması: DrivAer

Year 2023, Volume: 28 Issue: 3, 1127 - 1138, 29.12.2023

Oğuz Baş , Mustafa Atakan Akar , Coskun Özalp

https://doi.org/10.53433/yyufbed.1206050

Abstract

Bu çalışmada bir HAD simülasyonunda, akış alanının ağ çözünürlüğünün yeterli olup olmadığını belirlemek için yapılan ağ bağımsızlığı testlerine Richardson Ekstrapolasyonu ve ağ yakınsama indeksi (GCI) yaklaşımı uygulaması gerçekleştirilmiştir. Simülasyonlarda son yıllarda popüler hale gelen DrivAer jenerik araç geometrisi, aerodinamik sürükleme kuvveti bakımından incelenmiştir. Ansys Fluent yazılımı kullanılarak kapalı gövde fastback, estateback ve notchback modellerinin simülasyonları gerçekleştirilmiştir. Ağ elemanı sayıları artırılarak oluşturulmuş üç farklı ağ çözünürlüğünün yanısıra, dördüncü bir ağ seviyesi, GCI’ inden yararlanılarak oluşturulmuş ve deneysel verilere yakınsama açısından test edilmiştir. Sonuç olarak, bu yeni ağ seviyesi ile ağ sayısında çok fazla artışa gerek kalmadan, bütün araç modellerinde deneysel verilere kıyasla sürükleme katsayısı (C_D) için hata oranı %3’ün altına indirilmiştir.

Keywords

Ağ yakınsama indeksi, Ağdan bağımsızlık, Richardson ekstrapolasyonu, Taşıt aerodinamiği

Supporting Institution

Çukurova Üniversitesi Bilimsel Araştırma Projeleri komisyonu (BAP)

Project Number

FDK-2021-13262

Thanks

Bu çalışma, Çukurova Üniversitesi Bilimsel Araştırma Projeleri komisyonu (BAP) tarafından FDK-2021-13262’nolu proje tarafından desteklenmiştir.

Applications of Grid Convergence Index and Richardson Extrapolation in CFD Simulations: DrivAer

Abstract

In this study, Richardson Extrapolation, and grid convergence index (GCI) approach was applied to the grid independence tests to determine whether the mesh resolution of the flow domain is sufficient in a CFD simulation. In CFD simulations, DrivAer generic vehicle geometry, which has become popular in recent years, has been investigated in terms of aerodynamic drag force. Simulations were performed on closed-body fastback, estateback, and notchback models by using Ansys Fluent software. In addition to three different grid resolutions created by increasing the number of grid elements, a fourth grid level was created by using GCI and tested in terms of convergence to the experimental data. As a result, for all vehicle models, with this new grid level, the error rate for the coefficient of drag (C_D) was reduced to less than 3% compared to the experimental data, without the need for a large increase in the grid number.

Keywords

Grid convergence index, Grid independency, Richardson extrapolation, Vehicle aerodynamics

Project Number

FDK-2021-13262

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