Fuel-tank sloshing is the oscillation of the free fuel surface in a partially filled tank caused by rapid acceleration, braking, cornering, and curb strikes. On a race track these transient loads are large and abrupt, so the moving fuel can generate waves, impact internal walls, and momentarily uncover the pickup. This “sloshing” shifts mass, creates pressure loads on the tank walls, and risks uncovering the pickup. In racing, even a momentary loss of fuel supply can cause hesitation, reduced performance, or mechanical damage. To manage this, tanks are equipped with baffles, surge pots, or anti-slosh foam that dampen wave motion and ensure reliable pickup coverage. Simulation helps engineers predict how fuel behaves under track conditions, evaluate suppression measures, and optimize designs for both performance and durability. The simulation approach used here builds on our previous validated tank sloshing case , demonstrating the reliability of shonDy for predicting free-surface dynamics.
Case Description
The driving conditions for this study were based on acceleration data recorded during a private track session at the Lausitzring, kindly provided to us for simulation purposes. The dataset was collected with the Porsche Track Precision App and represents a complete lap.
For the analysis, a generic fuel tank model from an open-source library was used instead of the original vehicle tank. This approach allowed us to focus on the sloshing behavior itself without relying on proprietary geometry. In a subsequent step, the same tank was modified to include baffles in both longitudinal and lateral directions, enabling a direct comparison of fuel motion with and without suppression features. The geometry of both tank variants is shown in the images below.
The tanks have a capacity of around 60 L, but were filled with 20 L during the simulations. The complete lap was simulated to capture representative maneuvers—braking, cornering, and acceleration—and to evaluate how fuel movement and pickup coverage evolve over time. In this case study, the main focus is on the lateral movement of the fuel.
Results
The first video shows an overview of the simulation with the tank in the no-baffles configuration. The footage begins as the driver approaches Turn 1 (T1). The video is split into two segments: the first covers T1 to T5, and the second spans T12 to the finish line.
In the upper half of the video, the simulated tank and hence, the movement of the fuel can be observed. Even under relatively moderate driving conditions—where the driver is not pushing the car to its limit—the fuel exhibits strong lateral motion in response to track forces.
This demonstrates that sloshing is already noticeable under typical race-track conditions. In high-performance scenarios, where every tenth of a second matters, even these small mass shifts can negatively affect vehicle balance and handling.
The second video focuses on Turns 1 to 5, showing the tank in both configurations: with and without baffles.
Visual observation reveals a clear difference in fluid behavior:
- With baffles, the fluid is more evenly distributed and its movement is damped. The final position of the mass center is the same as without baffles, but the fluid takes longer to get there as it passes through the baffles.
- Without baffles, the fluid remains compact, shifting rapidly from one side to the other.
This observation is directly supported by the visualized centers of mass in the lateral direction, which are shown in the video:
- The green cross represents the center of mass (CoM) of the fluid without baffles.
- The yellow cross represents the CoM with baffles.
It is clearly visible that at the start of the turn, the green cross moves faster laterally than the yellow cross, confirming that baffles significantly reduce rapid mass shifts, improving stability.
Furthermore, this behavior is confirmed by the diagram below, which shows the velocity of the center of mass over time. It can be clearly seen that the CoM without baffles moves significantly faster than with baffles—at times reaching double or even triple the velocity. The spikes in velocity are also much sharper in the no-baffles case, indicating stronger acceleration and deceleration of the fluid. In contrast, the velocity distribution with baffles is broader and smoother, demonstrating the damping effect of the baffle structures.
The next diagram compares fuel coverage at the pickup. Baffles are expected to improve this coverage, ensuring a smoother and more reliable fuel intake.
For the investigation, a small sample window was placed directly in front of the pickup. This allowed monitoring of how much fluid is available at the pickup at any given time, providing insight into the effectiveness of the intake (see image below).
The diagram shows that baffles improve pickup coverage only slightly under the simulated conditions. Nonetheless, this small improvement, combined with the further damping of the center of mass motion, could serve as a starting point for baffle optimization in future designs.
Summary
In this case study, a full-lap simulation of a partially filled fuel tank on the Lausitzring “Grand Prix Layout” was performed to investigate tank sloshing under real driving conditions. Acceleration data recorded during a private track session was used to replicate braking, cornering, and acceleration maneuvers.
A generic tank model from an open-source library was simulated in two configurations: without baffles and with baffles in both longitudinal and lateral directions. The simulations visualized fuel movement, lateral mass shifts, and center of mass behavior throughout the lap. Additionally, fuel coverage at the pickup was monitored via a small sample window to quantify fluid availability over time.
The results demonstrate that transient free-surface CFD can capture the dynamic behavior of fuel in a tank under realistic race-track conditions. These simulations provide a foundation for evaluating and optimizing tank geometries, baffle placement, and fuel intake design, allowing engineers to test design modifications virtually before physical prototyping.
