March 15, 2006, 10:00 a.m. EST

Advanced science and Automation Corp. to develop the capability to model liquid sloshing in tanker trucks.

Indianapolis, IN- Advanced Science and Automaton Corp. (ASA www.ascience.com) received $850K from the US Army RDECOM-TARDEC, Warren, MI (tardec.army.mil) under an SBIR contract and a $100K grant from Indiana 21st century Research and technology fund (www.21fund.org) to develop a computational tool for time-accurate simulation of coupled CFD and multibody dynamics of tanker trucks with sloshing liquid payloads, that includes integrated pre-processor, solver, and post-processor.

The pre-processor consists of IVRESS (used for interactive 3D display and manipulation of the model) and IVRESS-Editor (hierarchical model tree editor). The pre-processor allows constructing an object-oriented hierarchical "preliminary" model of the vehicle, tank, and terrain. The pre-processor includes an automatic mesh generator for generating the finite element (FE) model from the preliminary model.

The DIS parallel explicit-time integration finite element (FE) code is used to generate the coupled dynamic response of the vehicle, tank, and fluid. The FE model consists of hexahedral, beam, and truss solid elements, rigid bodies, joints, actuators, hexahedral fluid elements, and quadrilateral fluid-solid interface elements. Normal contact between the vehicle's tire and the terrain (or other rigid/flexible bodies) is modeled using a penalty formulation. An asperity-based friction model is used to model joint and contact friction. The tank can be modeled as a flexible body (using brick-shell elements) or as a rigid body. For the flexible tank case, the fluid mesh is modeled as a very light and compliant solid mesh which allows the fluid mesh to move/deform along with the tank. For the rigid tank the fluid mesh moves as a rigid body with the tank. The ALE formulation is used in both cases to model the rigid body motion and/or deformation of the fluid mesh. The fluid governing equations of motion are the incompressible Navier-Stokes equations along with a large-eddy simulation (LES) turbulence model. The fluid's free-surface is modeled using a mass conserving volume-of-fluid (VOF) based algorithm.

Similar to the pre-processor, the post-processor consists of IVRESS and IVRESS-Editor. It allows near-photorealistic visualization of animations of: 1) liquid free-surface and iso-surfaces; 2) vehicle, terrain and surroundings; 3) colored/contoured surfaces, 4) surface/volume arrows, 5) stream/streak/path-lines. Users can control the visualization using the IVRESS-editor or a clickable hierarchical list of natural-language commands (using LEA).

Two validation studies will be conducted where the simulation results predicted using the computational model will be compared with physical experiments. The first study will use a small test fixture consisting of a rigid baffled tank mounted on suspension springs. The springs are connected to a rigid frame mounted on two linear hydraulic-actuators. The second study will use a full-scale army heavy class tactical trailer carrying a water tank. The trailer will be placed on an n-post motion base simulator which allows harmonic/ramp pitch, roll and stir excitations of the vehicle to simulate typical road maneuvers such as lane-change and going over bumps/potholes. Experiments will be carried out with various tank fill levels and baffle configurations.

Tanker trucks are used to transport liquids (such as fuels, water and various liquid chemicals) from production facilities to distribution outlets. They provide the most flexible and readily deployable form of liquid transportation. Improving the design of tanker vehicles by increasing their stability, liquid carrying capacity and/or maximum allowable safe speed will have a significant positive impact on the US civilian and military interests. The proposed simulation tool will help designers better understand how the motion of the fluid affects vehicle stability under various vehicle operating conditions. The simulation tool will help designers improve the design of tanker vehicles (e.g. optimize the vehicle's suspension system, optimize the tank geometry, and/or optimize the tank's baffles). The simulation tool will ultimately allow increasing the vehicle's stability and reducing the risk of tanker vehicle accidents. The proposed tool can be used in other applications involving liquid sloshing in tanks, including, ship and air-tankers, liquid fuel rocket tanks, spacecraft liquid fuel tanks, earthmoving equipment hydraulic fluid tanks, and automotive fuel tanks.

About Advanced Science and Automation Corp.

Advanced Science and Automation Corp. (ASA) mission is to provide state-of-the-art simulation and visualization solutions for our customers. ASA's Products include DIS (inclduing DIS/CFD, DIS/Belt, and DIS/Tire) time-accurate explicit finite element solver, and IVRESS object-oriented scene-graph based virtual-reality visualization engine. For more information, please visit www.ascience.com.

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