LEWICE (LEWis ICE accretion program) is a software used by literally hundreds of users in the aeronautics community for predicting ice shapes, collections efficiencies, and anti-icing heat requirements. LEWICE performs its analysis in minutes on a desktop PC, allowing the user to run several parameter studies for design purposes. The ice shape predictions have been used to assess performance degradation both as an input to a CFD program or experimentally in flight or in a wind tunnel. The ice shape predictions have been validated against a wide variety of experimental conditions as published in the following report.
The computer code LEWICE embodies an analytical ice accretion model that evaluates the thermodynamics of the freezing process that occurs when supercooled droplets impinge on a body. The atmospheric parameters of temperature, pressure, and velocity, and the meteorological parameters of liquid water content (LWC), droplet diameter, and relative humidity are specified and used to determine the shape of the ice accretion. The surface of the clean (un-iced) geometry is defined by segments joining a set of discrete body coordinates. The code consists of four major modules. They are 1) the flow field calculation, 2) the particle trajectory and impingement calculation, 3) the thermodynamic and ice growth calculation, and 4) the modification of the current geometry by addition of the ice growth. LEWICE applies a time-stepping procedure to "grow" the ice accretion. Initially, the flow field and droplet impingement characteristics are determined for the clean geometry. The ice growth rate on each segment defining the surface is then determined by applying the thermodynamic model. When a time increment is specified, this growth rate can be interpreted as an ice thickness and the body coordinates are adjusted to account for the accreted ice. This procedure is repeated, beginning with the calculation of the flow field about the iced geometry, then continued until the desired icing time has been reached..
LEWICE 2.0 (current version): LEWICE 2.0 is different from its predecessors not through wholesale changes in the physical models but rather through an extensive effort to adjust, test and document the code to ensure: that the code runs correctly for all of the cases shown; that the quality of output is maintained across platforms and compilers; that the effects of time step and spacing have been minimized and demonstrated; that the code inputs and outputs are consistent and easy to understand; that the structure and documentation within the code makes it readily modifiable to those outside the standard LEWICE development team; and that the code has been validated in a quantified manner against the largest possible amount of experimental data.
For a complete descriptiion of current and previous LEWICE versions, please consult our versions page.
How to obtain the software: Current policy requires that all requests for software codes be submitted in writing. Send your request to:
Mary Wadel,Chief, Icing Branch
NASA Glenn Research Center
21000 Brookpark Rd., MS 11-2
Cleveland, OH 44135