So Autodesk has a plug-in for Revit that allows you to export your model as a .nwc file.
Here is a little about the plug-in from the download web site:
The distributable NWC file exporter enables project teams using Autodesk® Naviswork® software to generate whole-project models for simulation and analysis. Project team members can generate the optimized NWC file directly from their design applications. This capability is provided without necessitating a licensed seat of Autodesk Navisworks 2012 software on the same machine. The NWC exporter works with a range of products, including the AutoCAD®-based and Revit®-based Autodesk products, as well as Autodesk® 3ds Max®, Bentley MicroStation®, and Graphisoft ArchiCAD® software. The NWC file format supports transfer of both object geometry and associated metadata from the design applications into Autodesk Navisworks 2012 software.
Here is a link to the download: http://usa.autodesk.com/adsk/servlet/pc/item?id=13947462&siteID=123112
The tool will be available to you under the External tools icon on the Add-Ins tab.