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A Note on How to Read This Page

None of the researchers listed below were asked by Liquid Surge Control to validate Surge Busters. Most of this work predates Surge Busters, or was conducted independently of any commercial relationship with us.

What they validated, broadly and across many institutions, is that baffles measurably reduce sloshing energy, that surge peaks at partial fill, and that fixed baffles offer no lateral-rollover protection. The narrower claim that a floating design specifically outperforms a fixed one rests on Budwig's test together with Kang et al.'s (2019) floating-baffle study. It has less independent replication behind it than the other findings on this page, and this page says so rather than implying otherwise.

Quick Reference: Claim to Citation

The Primary Source: Budwig, University of Idaho (2004)

Dr. Ralph S. Budwig, Professor and Chair, Department of Mechanical Engineering, University of Idaho, 2,300+ academic citations, ran an independent tilt-table test in 2004, at Liquid Surge Control’s request and at no cost to the company.

→ Read the summary: The Science Behind the 96.7%

→ Download the original Budwig study (PDF)

Everything below either independently confirms the physics this test demonstrated, or extends it into related questions: why floating baffles work the way they do, why partial loads are the most dangerous, and why fixed baffles can't address lateral rollover risk.

How We Calculate Surge Force at Any Fill Level or Tank Size

Budwig's report documents one physical measurement: 26,480 lbf without Surge Busters, 860 lbf with Surge Busters, at 80% fill, 1,000 gallons, 40 mph, CoF 0.60. It does not contain a fill-level curve or a per-liquid density formula. Those are ours, built to extend a single measured point into a usable model across any fill level, liquid, or tank size. Speed is deliberately not a variable here, see below. Here is exactly what each piece rests on.

Speed is not a variable

An earlier version of this page scaled surge force as (speed ÷ 40)², on the reasoning that kinetic energy is proportional to velocity squared. That reasoning justifies energy scaling, not force scaling, and the two only coincide under specific braking assumptions. Emergency-braking deceleration is friction-limited, capped by tire-road grip, not by initial speed, which is standard, decades-old material in heavy-vehicle brake testing and accident reconstruction, and is also the modeling convention used in the tank-truck slosh literature itself: Kang, Rakheja & Stiharu (2002) and related studies specify a deceleration level directly (e.g., "0.3g ramp-step") rather than deriving one from speed. Surge force in this model is therefore identical at 40, 55, and 70 mph for a given fill level, liquid, tank size, and road surface, and the site now reports a single reference figure (40 mph, matching Budwig's tested condition) rather than three.

Fill-level dependence follows fill × (1 − fill)

The documented phenomenon, zero surge at empty, zero at full, a peak somewhere near the middle, is independently established across multiple studies (Yan & Rakheja, 2009; Kolaei, Rakheja & Richard, 2014 to 2017; Biswal et al., 2006). The specific function fill × (1 − fill) is the simplest mathematical form that produces exactly that shape. It is an engineering representation of a confirmed phenomenon, not a formula published in those papers.

Density-linear scaling, K = 3.598 × (density ÷ 7.10)

Follows from F = ma at a fixed volume and deceleration profile: force scales linearly with mass, and mass scales linearly with density. This is a reasonable first-principles assumption, not an explicit published finding.

The 47,000 lb reference payload and the 0.20 divisor

These constants were calibrated specifically to reproduce Budwig's one measured result, 26,480 lbf at 80% fill, 1,000 gallons, 40 mph, CoF 0.60, to within 0.1%. This is calibration against a known test point, not derivation. It is legitimate engineering practice, and it is described accurately here as exactly that.

What's fixed versus what you control when using the calculator

Everything on this page so far describes the model itself: the 47,000 lb reference payload, the 0.20 divisor, and the K constants (3.598, 7.10) are fixed calibration values, the same for every calculation, never adjustable. They are not inputs. Your tank capacity, liquid type and density, fill level, empty vehicle weight, axle and tire counts, road surface or custom coefficient of friction, and GVW limit inputs are fully editable in the calculator and drive every live result. The fixed constants are what make the model consistent; your inputs are what make it yours.

→ Try the Calculator

In short: the fill-dependence shape has independent grounding outside of Budwig, and speed has been deliberately removed as a variable based on separate, independent grounding (see above). The model's specific constants are calibrated to Budwig's single measured result. The complete formula, as assembled, is Liquid Surge Control's engineering model, anchored to and validated against Budwig's test, not a formula published in the Budwig report itself.

Why Floating Baffles Work (Core Mechanism)

Fixed baffles are welded to the tank wall. When liquid surges into them, the force transfers into the wall, and from there, into the truck. The baffle redirects the force; it doesn't remove it.

Surge Busters float freely. As the wave moves, they move with it, breaking the wave's rhythm into smaller, disorganized eddies that cancel each other out, inside the tank, before the force ever reaches the truck.

This isn't a new idea. It's the same principle that's protected liquid fuel in spacecraft for sixty years.

Note on Xie & Zhao (2021): this paper studies actively, algorithmically controlled baffles (via reinforcement learning), a powered mechanism, not the passive floating design Surge Busters use. It supports the broader principle that baffle motion affects damping, not a direct comparison to Surge Busters' specific mechanism.

What This Establishes

Surge Busters float freely and flex against surge energy. They don't transfer force to the tank wall or the truck chassis. Unlike welded baffles, which can only resist forward-back surge, floating baffles respond in every direction.

Why Partial Loads Are the Most Dangerous (The Bell Curve)

Surge force isn't proportional to how much liquid is in the tank. It peaks around 50 to 52% fill, not at full load, and not empty. A truck that "isn't carrying much" is often carrying the worst possible load for surge.

Why Fixed Baffles Can't Prevent Rollovers (Lateral Surge)

Fixed baffles run front-to-back. They do nothing about side-to-side motion, the kind that happens during cornering, lane changes, or evasive maneuvers, and the kind most directly tied to rollover risk.

Why 96.7% Is the Right Number (Kinetic Energy Dissipation)

The 96.7% figure comes from Budwig's tilt-table test. These papers independently establish that baffle geometry and placement measurably increase sloshing energy dissipation through mechanisms like flow separation and vortex shedding, the general engineering basis for why baffles work at all. They study fixed baffle configurations, not floating ones, so they corroborate that baffles dissipate energy, not the specific magnitude or the floating-versus-fixed comparison. The 96.7% figure, and the claim that a floating design outperforms a fixed one, rest on Budwig's tilt-table measurement alone.

Supporting Research: The Problem, Independently Documented

These studies don't examine floating baffles specifically. They document the underlying sloshing problem in tank trucks and the conditions that make it dangerous. They establish the problem Surge Busters solve, independent of Surge Busters themselves.

Foundational References: Why This Field Is Taken Seriously

Liquid slosh control isn't a niche concern invented for tank trucks. It's a flight-critical engineering discipline. The same physics that keeps liquid fuel and oxygen stable in spacecraft applies, at smaller scale, to a half-full tank on the highway.

Title may vary slightly at the source. Worth verifying before publishing that this is the same paper.