Calculating
The simulator animates this model's numbers (downflow at the annular velocity, bubbles rising at their rise speed and merging at each disc). It illustrates the model. It is not CFD. Surrounding ground is drawn generically, not from a well log.
Velocity race
Air separates when it can rise faster than the water carries it down. Discs cannot lower the average downward velocity, which is fixed by flow ÷ annulus area. They break the cascade, spread the flow, and make small bubbles merge into larger ones that rise faster.
Operating envelope
Fabrication
Parts for this well
Hydraulics
Design optimizer
Searches every standard hole size and pitch for this well, keeps only designs that pass every rule (head-loss window per disc, flow-loss limit, ligament and hole at least the plate thickness), then ranks them. Pitches are rounded up to 1/16 in so they can be cut as drawn.
Each dot is a candidate disc, sized by hole diameter. Blue dots pass every rule. Outlined dots form the trade-off frontier: you cannot cut less steel without losing more flow. The green ring is the top-ranked design. Hover a dot for details.
Ranked designs
Monte Carlo risk
Annular velocity spread
Where the downward velocity lands across all runs, against the two rise limits.
What drives it
Each bar swings one input across its uncertainty range (set under “Uncertainty”) with everything else at design.
Compare designs
Save the current design, change inputs, save again, and compare side by side. Saved designs stay in this browser.
Design engineer
Claude reviews the live design (inputs, results, optimizer and risk runs) as a downhole hydraulics engineer. Answers are added to the design report. Each question uses your own Claude usage.
How the workstation works
Physics from standard references
- Annular velocity
V = Q_above ÷ (π/4 × (casing ID² − column OD²)). Only water entering above the intake moves down the annulus. - Small-bubble rise, default 0.75 ft/s: terminal rise of 2–5 mm air bubbles in water (Clift, Grace & Weber). Editable.
- Merged gas rise in an annulus
U = (0.32 + 0.016 Dc/Dt) √(g Dt)(Kelessidis & Dukler), times your safety factor, capped at your cap-bubble limit (default 1.0 ft/s). The formula was fitted on small annuli; in large casings big bubbles break into cap bubbles. - Core velocity
Vc = C0 × V. Bubbles ride the faster core of the flow (drift-flux distribution coefficient, default 1.2). Every regime check uses Vc, not the average. - Disc head loss, thin perforated plate:
ζ = (0.707√(1−φ) + 1 − φ)² ÷ φ²on annular velocity (Idelchik). φ counts holes, ports, the casing gap and the segment joint slots. For plates thicker than the hole it overstates the loss: conservative for flow loss, optimistic for the minimum-loss check. - NPSH available: atmospheric head at site elevation + submergence − vapor pressure − disc losses. Intake and screen losses are not included.
- Flow change: stack head loss ÷ pump curve slope at the duty point.
Disc construction modeled
- Perforated segments run from the column bore to the casing. A split hub ring clamps over them and bolts through to each segment, as in the fabricated discs.
- Pass-through ports straddle the hub edge and the hub is notched around them. Holes keep clear of the hub, ports, joints and the outer edge by the edge margin.
- The hub splits at two segment joints, so no bolt sits on a split.
- Not modeled: fastener sizes beyond the bolt hole, coupling clearance, centralizers, and how the stack is supported on the column. Detail those with the fabricator.
Analysis tools
- Optimizer: exhaustive search over standard hole sizes and pitches under hard engineering constraints, a weighted ranking, and the trade-off (Pareto) frontier between flow loss and cutting length.
- Monte Carlo risk: thousands of runs centred on the design pumping level (pumping level + seasonal allowance), with pumping level, flow, share of flow from above, bubble rise and pump curve slope drawn from triangular distributions over your ranges. Seeded, so the same inputs always give the same answer.
- Sensitivity: one input at a time across the same ranges.
Field rules to calibrate
- Disc count, falling water: one disc per “fall or wetted screen per disc” of exposed perforation above the design pumping level, plus one coalescing disc when the core velocity beats small-bubble rise (minimum two).
- Disc count, aquifer air: one disc per the same length of wetted screen above the intake; minimum one, or two when the core velocity beats small-bubble rise. Both sources: the larger count.
- Placement: falling water starts below the design pumping level at your spacing; aquifer air builds up from the intake clearance at your spacing; both spreads the discs evenly over the zone, never closer than your spacing.
- Head-loss window per disc: enough to break the cascade's momentum, not so much it costs flow.
What it does not know
- Real bubble sizes, the air fraction, and how much of the casing wall the cascade covers.
- Whether gas collects under a disc and releases in slugs. Watch motor amps and discharge for air after install.
- Casing condition: out-of-round, weld beads, scale or a liner change the usable disc OD. Run a drift check first.
Results are a design aid generated from the inputs shown. They are not a stamped engineering document.