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In flight ice accretion is a weather related hazard that has the potential to cause reduced performance or even failure of various aircraft components. Engineers at NASA have developed the LEWICE codes, which simulate how the water droplets from a cloud impact and grow ice on vehicles in flight. This allows for icing related analysis and design to be addressed earlier in the design process, such as the placement and extent of ice protection systems. These efforts help ensure the safety of airplanes, by preventing potential accidents caused by exposure to icing, through improved effectiveness of design and certification efforts.


LEWICE is a software program 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.


LEWICE3D prediction of collection efficiency (color contours) and the resulting ice shape (at discrete cuts) along a wing.

LEWICE3D is a post processor that utilizes the fluid flow simulated by third-part CFD software to compute various parameters associated with icing risk. The three main components of LEWICE3D compute: 1) Water droplet trajectories 2) Collection efficiency (i.e. droplet impingement) 3) Resulting ice shapes. LEWICE3D takes advantage of the embarrassingly parallel nature of the droplet trajectory portion of the code to allow the user to scale computational resources with problem size ensuring the simulations remain computationally fast. Results from LEWICE3D have been compared to an extensive database of ice shape profiles obtained from experimental measurements and the software has shown a very good ability to reproduce such profiles under most conditions of interest to the aviation community. This validation effort has made the LEWICE3D software one of the most extensively tested ice accretion prediction tools available.

Software Requests

Version are available for download through NASA’s Software Catalog.

To request a copy of LEWICE or LEWICE3D visit: NASA Software

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