Domain: Engineering — Chemical Engineering
Target concept: Hot-air drying

Video generation prompt: The wet solid material (wet salt) was evenly spread on the tray of the hot air dryer. The tray was placed on a balance, with a material thickness of 5 mm. The hot air temperature was set to 60°C, and the air velocity was set to 1 m/s. The drying device was activated and operated continuously. The front view of the setup, including the tray and the balance, was continuously recorded for several hours, and the movement of the balance pointer was observed.

Evaluation guide:
(i) Target concept: Convective drying of hygroscopic crystalline solids under controlled thermal and hydrodynamic conditions.
Minimum mechanism: Moisture must reside on solid surface/in pores; hot air must contact material; mass loss must occur solely via evaporation (not sublimation, decomposition, or runoff); balance must transduce mass change into visible pointer displacement.
(ii)Storyline: [Frame 0] Tray placed on balance pan with wet salt evenly distributed → [Frame 1–N] Dryer activates; airflow begins; pointer initiates smooth downward motion → [Ongoing] Salt texture evolves from clumped/moist to dispersed/drier while remaining solid and unchanged in color → [Entire sequence] Front-view camera remains static; all objects maintain fixed spatial relationships; pointer motion is monotonic and uninterrupted; no external interference or physical inconsistency occurs.

Manual:
Experimental Procedure
1. Place tray on balance pan.
2. Evenly spread wet salt on tray to form uniform layer.
3. Activate hot air dryer (60°C, 1 m/s).
4. Record front view continuously.
Observation of Experimental Phenomena
- Wet salt appears moist (clumped, slightly reflective surface).
- Balance pointer moves downward continuously during operation.
- Tray remains stationary on balance; no vibration or displacement.
Summary of Experimental Principles
Hot-air drying removes moisture from wet solids via convective heat and mass transfer. Constant temperature and airflow enable steady-state evaporation, resulting in measurable mass loss over time.

Prompt Grounding rubric:
level_1: No wet solid material visible on tray; no balance present in frame; no hot air dryer structure visible; no front-view setup shown; none of the required objects (tray, balance, wet salt, dryer housing) appear.
level_2: At least one required object appears (e.g., tray or balance), but wet salt is absent or unidentifiable as wet solid; dryer activation not implied; front view not established; spatial arrangement inconsistent with posted_prompt (e.g., top-down or oblique angle).
level_3: Tray with visibly wet solid material (light-colored granular substance with surface moisture sheen or clumping) is present on a balance; front-view camera angle shows both tray and balance simultaneously in same scene; hot air dryer housing or inlet duct is partially visible; all core objects (wet salt, tray, balance, dryer context) are present and correctly type-identified.
level_4: All elements from 3-score are present AND the tray is placed directly on the balance pan (not beside or above it); wet salt is evenly spread (uniform coverage across tray surface, no bare patches or thick piles); dryer activation is visually implied by airflow indicator (e.g., visible air stream distortion, flag motion, or labeled “ON” status light), with no contradictory cues (e.g., power-off label, disconnected duct).
level_5: All elements from 4-score are present AND the material thickness is visually consistent with a single uniform layer (no overlapping grains, no vertical stacking, no visible substrate through material); balance pointer is fully visible and stationary (not blurred or cropped); front view is strictly orthogonal (no perspective skew, no foreshortening of tray edges); no extraneous objects (e.g., hands, tools, labels) enter frame at any time.

Scientific and Causal Correctness rubric:
level_1: Wet salt appears dry (powdery, dusty, cracked, or fully white without moisture cues); balance pointer shows no deflection or movement inconsistent with mass loss; no observable drying phenomenon; material changes contradict hot-air drying (e.g., melting, bubbling, discoloration to yellow/brown).
level_2: Wet salt is present but shows no visual sign of moisture (no surface reflectivity, no clumping, no damp texture); balance pointer is absent, occluded, or frozen in place; no causal link between dryer operation and observed state; material behaves like dry powder from start to end.
level_3: Wet salt appears moist (visible surface sheen, slight clumping, soft granular texture); balance pointer is visible and shows continuous downward movement (indicating mass loss) during recording; dryer is active (airflow implied); mass loss is temporally aligned with dryer operation, with no reversal or pause in pointer motion during active phase.
level_4: All elements from 3-score are present AND pointer motion is smooth and monotonic (no jerks, rebounds, or stalls); wet salt maintains solid state throughout (no liquefaction, no dissolution, no vapor plume); color remains unchanged (no thermal browning or oxidation); drying progression is visually plausible (e.g., gradual reduction in clump size or sheen intensity over time).
level_5: All elements from 4-score are present AND pointer displacement is exclusively downward (no upward motion, no oscillation); wet salt exhibits progressive textural change: initial clumping → partial separation → fine dispersion, all while remaining solid and non-adhesive; no visual artifact contradicts constant air velocity/temperature (e.g., no condensation, no dust suspension inconsistent with 1 m/s flow).

Spatiotemporal Consistency rubric:
level_1: Objects teleport (e.g., tray appears/disappears mid-video); balance pointer jumps discontinuously; lighting changes abruptly between frames; tray or balance rotates or shifts position without motion continuity; camera viewpoint changes (pan/tilt/zoom).
level_2: One or more major spatiotemporal breaks: tray repositions without visible motion; pointer resets to zero; shadow direction flips; balance base disconnects from floor; tray floats or hovers; inter-frame flicker or severe stutter dominates >30% of frames.
level_3: All objects maintain fixed relative positions (tray centered on balance pan, dryer housing static in background); pointer moves continuously with no jumps or freezes; lighting is stable (no flash, no strobing, no cast shadow migration); camera remains locked in front-view orthographic framing throughout.
level_4: All elements from 3-score are present AND motion is physically coherent: pointer movement matches expected inertia (smooth acceleration/deceleration, no instant velocity change); tray does not vibrate or rattle despite airflow; no parallax violation (e.g., foreground/background misalignment across frames); no inter-frame tearing or ghosting affecting key objects.
level_5: All elements from 4-score are present AND every frame preserves rigid spatial hierarchy: tray surface remains parallel to balance pan plane; pointer pivot point is fixed and unobscured; airflow indicators (if present) move synchronously with pointer motion (e.g., flag flutter frequency correlates with pointer speed); no frame drop, no compression artifacts distorting shape or motion.