Cylindrical‐conical spouted bed dynamics: Laminar and turbulent flow predictions
Bibliographic record
Abstract
Abstract This work numerically studies transient behaviour of particulate flows in a cylindrical‐conical spouted bed in terms of comparative analysis of different models’ predictions. Two approaches were used: a laminar flow model and a turbulent flow model. As a reference case, we consider experimental studies by He et al.,[14,15] where the profiles of vertical particle velocities and the void fraction in the spout and the fountain of a full‐column spout bed were measured. In this work we used the Euler‐Euler unsteady multiphase model with the Syamlal‐O'Brien, Gidaspow, and Wen‐Yu drag models available in commercial CFD software Fluent 14.0. Analysis of results obtained by the use of laminar and turbulent flow models revealed almost identical solid and gas phase velocities and phase fractions within the spouted bed region. We found that the turbulence plays a significant role only in the gas phase above the spouted bed and it does not have any influence on the solid phase. Comparing our simulation results in the form of time‐averaged vertical velocity of the solid phase against experimental data showed acceptable agreement in the spout and very good agreement in the fountain region. Numerical simulations with the Syamlal‐O'Brien drag model gave better agreement with experimental data than results obtained using the Gidaspow and Wen‐Yu drag models. To analyze the transient behaviour of the spouted bed, we use the volume‐averaged particle velocity and gas phase velocity. The analysis of their time histories showed that the start up time is 2–3 s. The developed unsteady regime is reached after 4–5 s. Additionally we studied numerically the influence of different discretization schemes for convective terms on the final results. We found that the use of 1st order upwind scheme gives a steady state solution for both models, laminar and turbulent. Finally, we investigated the influence of the restitution coefficient on the transient characteristics of a cylindrical‐conical spouted bed. A decrease in the value of the restitution coefficient leads to an increase in the period of oscillations of the volume‐averaged velocities of the gas and solid phases.
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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 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".