The Effects of Open and Closed Diffusers on the Wake Structures of an Ahmed Body
Bibliographic record
Abstract
Abstract This study presents a comparative analysis on the effect that a diffuser with and without endplates has on the development of coherent wake structures behind an Ahmed body. To achieve this, a diffuser was located underside at the trailing edge with an angle of 10°. Each case was performed at a Reynolds number of ReL = 9.7 × 104. A numerical simulation using an Improved Delayed Detached Eddy Simulation model was employed to determine the time-averaged location of different coherent structures, such as streamwise vortices, recirculation zones, and separated flow in the diffuser. This included the shear-layer, corner vortices, and the edge-tip vortices formed from the diffuser. Analysis of the time-averaged velocity in the wake show stronger upwash flow for the closed diffuser case compared to the open diffuser. Due to the presence of the diffuser, the typical corner vortex is diminished prior to the end of the Ahmed body. A new vortex is generated on the edge of the diffuser, extending into the wake behind the body. The results show that in the open diffuser case, edge-tip vortices are significantly weaker due to increased fluid entrainment. In contrast, the closed diffuser generates stronger, more coherent vortices, which persist further downstream.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".