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RIPPLE: A Computer Program for Incompressible Flows with Free Surfaces
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Abstract: RIPPLE: A Computer Program for Incompressible Flows with Free Surfaces is a computer program for modeling transient, two-dimensional, incompressible fluid flows with surface tension on free surfaces of general topology. Incompressible free surface fluid flows form an integral part of natural and industrial processes. The fluid behavior can be especially difficult to understand and quantify when the free surfaces have appreciable surface tension and are arbitrarily complex in topology. Examples of such flows can be found in nuclear reactor thermal hydraulics, internalcombustion-engine fuel sprayers, ink-jet printers, the application of industrial surfactants, raindrop formation, casting and mold filling processes, drop/bubble dynamics, and in cryogenic liquids in a micro-gravity environment. Modeling these types of flows poses a significant challenge because a required boundary condition must be applied to a transient, irregular surface (the free surface) that is ideally a discontinuity. Surface tension frequently constrains the accuracy with which the resulting boundary condition is applied in numerical models.

In RIPPLE, surface tension at free surfaces is replaced by a volume force derived from the continuum surface force model. A two-step projection method is used to solve for incompressible flow, with the pressure Poisson equation solved via a robust incomplete Cholesky conjugate gradient technique. Momentum advection is estimated with a technique very similar to the weakly monotonic upwind method of van Leer. Flow obstacles and curved boundaries interior to the mesh are representable with a partial cell treatment that borrows from two-phase flow physics. The numerical scheme of RIPPLE is based on a finite difference solution of a coupled set of partial differential equations governing incompressible fluid flow. Finite difference solutions to the incompressible Navier-Stokes equations are obtained on an Eularian, rectilinear mesh in Cartesian or cylindrical geometries. Free surfaces are represented with volume-of-fluid data on the mesh. Surface tension is modeled as a volume force derived from the continuum surface force model. The continuum surface force model for surface tension gives RIPPLE both robustness and accuracy in modeling surface tension effects at the free surface. RIPPLE can also model wall adhesion effects.

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Description: Login to download RIPPLE: A Computer Program for Incompressible Flows with Free Surfaces.
Service Citation
Originators: National Technology Transfer Center
Title: RIPPLE: A Computer Program for Incompressible Flows with Free Surfaces
Provider: Open Channel foundation
ISO Topic Category
RIPPLE is written in Fortran 77 for use with computers running UNIX. RIPPLE has been successfully compiled and executed on a Sun SPARC workstation running SunOS 4.1.1. RIPPLE was developed in 1991.
Access Constraints
Users must login to use RIPPLE.

Distribution is permitted to citizens of most countries (EAR99). There may be a delay in processing requests from people who are not United States citizens, or who reside outside of the United States.
Service Provider
Open Channel Foundation

Service Provider Personnel
Phone: 773-334-8177
Fax: 773-334-8187
Email: info at
Contact Address:
Open Channel Foundation
1807 W. Sunnyside Avenue
Suite 301
City: Chicago
Province or State: Illinois
Postal Code: 60640
Country: USA
Distribution Media
Distribution_Media: Online
Fees: $1,250.00 (Domestic) $2,500.00 (International)
Phone: (301) 614-6898
Fax: 301-614-5268
Email: Tyler.B.Stevens at
Contact Address:
NASA Goddard Space Flight Center
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City: Greenbelt
Province or State: MD
Postal Code: 20771
Country: USA
Creation and Review Dates
SERF Creation Date: 2011-08-15
SERF Last Revision Date: 2011-08-16
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