Domain: Engineering — Hydraulic Engineering
Target concept: Water pressure

Video generation prompt: Two connected transparent containers are equipped with a valve in the middle. The left container is filled with 25 cm deep clear water, and the right container is filled with 10 cm deep clear water. Procedure: open the central valve, and record the water level changes and flow movement in both containers for the next 30 seconds.

Evaluation guide:
(i) Target concept: Hydrostatic pressure-driven flow between connected vessels until mechanical equilibrium is reached.
Minimum mechanism: Two open-top liquid columns connected at base; density uniform; gravity active; no external pumping or capillary dominance; container rigidity and vertical alignment maintained.
(ii)Storyline: [Phase 1: Static Setup] Two side-by-side transparent containers, visibly unequal water levels, closed central valve; all elements fully in frame, no motion. [Phase 2: Action Trigger] Valve opens via unambiguous mechanical motion (handle rotation/gate lift); no delay, no reversal. [Phase 3: Causal Flow] Immediate onset of left→right water movement; concurrent monotonic decrease/increase of respective levels; flow visibly decelerates as levels approach parity. [Phase 4: Equilibrium State] Motion ceases; surfaces become still and coplanar; no residual slope, oscillation, or disparity. [Perspective constraint]: Fixed frontal orthographic-like view; no camera movement, no oblique angle distorting level comparison; container tops and water surfaces fully visible for direct height judgment.

Manual:
Experimental Procedure
1. Place two identical transparent rectangular containers side-by-side.
2. Fill left container with clear water to 25 cm depth; fill right container with clear water to 10 cm depth.
3. Close central valve connecting them.
4. Open valve and record until water levels stabilize.
Observation of Experimental Phenomena
- Initially, left water level is visibly higher than right.
- Upon opening valve, water flows from left to right.
- Left level steadily decreases; right level steadily increases.
- Flow gradually slows; both levels converge to identical height.
Summary of Experimental Principles
- Water flows due to pressure difference caused by height difference (P = ρgh).
- Flow ceases when hydrostatic pressure equalizes → levels become equal.

Prompt Grounding rubric:
level_1: The scene shows fewer than two transparent containers, or they aren't joined by a visible central valve, or no water appears in one or both containers, or the two containers are stacked or set apart rather than placed next to each other.
level_2: Two transparent containers sit next to each other, but the valve between them is missing, sealed shut, or looks like a plain pipe with no visible mechanism; water shows up in only one container, or the water looks tinted or cloudy instead of clear; the valve is never shown opening.
level_3: Two transparent containers stand side by side joined by a visible central valve; both hold clear water, with the left container starting noticeably deeper than the right; the valve is manually opened (its handle turns or its gate lifts) before any water motion appears.
level_4: Everything in score 3 holds true, and in addition: the valve finishes opening before the water starts moving, both containers stay in their fixed spots for the whole clip, and nothing (hands, labels, other objects) blocks the view of the valve or the water surfaces.
level_5: Everything in score 4 holds true, and in addition: the two containers are visibly the same shape and width, the valve sits centered between them with matching connecting pipework on each side, and the curved water surface in each container stays visible both before and during the flow.

Scientific and Causal Correctness rubric:
level_1: The two water levels never change; or the water appears to flow upward or sideways without the levels ever coming together; or the clip implies the levels have equalized while they are still clearly unequal at the end.
level_2: Water moves the wrong way for the pressure difference: for example, flowing from the shallower right container into the deeper left one; or the flow stops while the levels are still unequal; or the right level ends up higher than the left; or flow starts even though the two levels began equal.
level_3: Water visibly flows from the left (25 cm) container into the right (10 cm) container; the left level steadily drops while the right level steadily climbs; both settle at the same final height; the flow visibly slows down as the two levels get close to each other.
level_4: Everything in score 3 holds true, and in addition: the flow runs the whole time without abruptly stopping and restarting or reversing back and forth; both water surfaces stay flat and level throughout, with no tilting, sloshing, or standing waves; no bubbles or turbulence get in the way of comparing the two levels.
level_5: Everything in score 4 holds true, and in addition: because the two containers share the same cross-section, the left level's drop and the right level's rise track each other in speed at every moment, and that shared speed slows down together as the height gap closes toward zero; both surfaces come to rest in the same still, flat shape once the heights match.

Spatiotemporal Consistency rubric:
level_1: A container suddenly shifts position, spins, or changes size between shots; the valve appears or disappears without ever being opened; the water surface visibly jumps or teleports between frames instead of moving smoothly; a shadow vanishes and then reappears with no change in the light; a container's edges bend or shear in a way a rigid container never would.
level_2: A container creeps noticeably away from its starting spot, more than ordinary handheld camera wobble would explain; the water surface skips, splits, or seems to show two levels at once instead of changing smoothly; the valve handle turns one way, reverses, and turns again before it finally opens; reflections on the water shift as if the light source itself had moved.
level_3: The two containers hold their ground and stay level from the first frame to the last, without drifting, spinning, or resizing; the valve handle moves in a single direction as it opens rather than wavering back and forth; the water surface changes height smoothly, never skipping, splitting, or layering; the shadows cast by the containers keep a constant direction and softness.
level_4: Everything in score 3 holds true, and in addition: the gap between the two containers' inner walls stays the same throughout, the camera never pans or zooms in a way that shifts the containers relative to one another, and reflections on the water stay aligned with the container walls as the level changes.
level_5: Everything in score 4 holds true, and in addition: reflections on the water shift smoothly and believably as each level changes, the curved meniscus in each container changes shape gradually instead of snapping flat or sharp, and the footage plays smoothly with no repeated, frozen, or flickering frames anywhere in the clip.