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RELAP5-3D © to Fluent CFD Software Coupling Richard R. Schultz Workshop: VHTR R&D Plan Hosted by: Academic Center of Excellence for Thermal Fluids and.

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Presentation on theme: "RELAP5-3D © to Fluent CFD Software Coupling Richard R. Schultz Workshop: VHTR R&D Plan Hosted by: Academic Center of Excellence for Thermal Fluids and."— Presentation transcript:

1 RELAP5-3D © to Fluent CFD Software Coupling Richard R. Schultz Workshop: VHTR R&D Plan Hosted by: Academic Center of Excellence for Thermal Fluids and Reactor Safety, Oregon State University September 19-20, 2005

2 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Project Summary & Other Considerations… RELAP5-3D © & Fluent coupling. –Importance –Benefits –How it was done –Status –Ongoing analysis of VHTR Other considerations

3 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Importance of Coupling Systems Analysis Codes to CFD Codes widely recognized … IAEA recently hosted a meeting to discuss: “…interest in the application of 3-dimensional CFD software as a supplement to or in combination with system codes, which provide the boundary conditions for CFD codes.” Problems under discussion include:  Evaluation of performance of passive safety features;  L ocal phenomena leading to cladding ruptures;  Multidimensional TH in various components;  Liquid/gas stratification and interface tracking; and  Bubble dynamics in suppression pools.”

4 VHTR R&D Plan Workshop Corvallis, OR September 19-20, To Address Such Issues… Fluent Corporation & INEEL embarked on project to couple Fluent CFD and RELAP5-3D © Fluent CFD was selected as collaborator by INEEL * because: –Fluent CFD demonstrated high quality—see CFD Forum results: C. J. Freitas, “Perspective: Selected Benchmarks from Commercial CFD Codes,” Journal of Fluid Mechanics, 117, 1995, pp. 208 to 218 –Extremely cooperative –High quality standard: ISO 9001:2000 –Largest user base and largest suite of applications (& probably largest suite of V&V cases). ____________________ * after contacting CFX, Fluent, and STAR-CD

5 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Fluent to RELAP5-3D © Coupling: Advantages Utilize system-wide macro modeling capability of RELAP5-3D Model some components of the system in detail using the micro-modeling features of FLUENT Courtesy of Fluent

6 VHTR R&D Plan Workshop Corvallis, OR September 19-20, The performance of the system depends on the flow through each component, and vice versa Boundary condition information is transferred back and forth between the two codes Both the system and component behaviors are more accurately predicted Benefits of Fluent & RELAP5-3D © Coupling Courtesy of Center for Multiphase Research, RPI

7 VHTR R&D Plan Workshop Corvallis, OR September 19-20, An Executive program controls the coupling of RELAP5-3D © to other codes using PVM PVMEXEC PVM RELAP-3DFLUENTCONTAIN Synchronous or Asynchronous coupling

8 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Coupling Protocol has been extensively checked out.. Most extensively by Bettis Atomic Power Laboratory Performed calculations with up to three codes coupled to RELAP5-3D © simultaneously, including the CFX CFD code. Grind time defined by CFD code when coupled with RELAP5-3D ©

9 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Coupling of RELAP5-3D © & Fluent is Semi-Implicit RELAP5-3D © & Fluent move forward time step-by-time step to perform calculation. Calculation only moves forward when convergent solution is achieved in both left and right computational domains. RELAP5-3D reactor physics can be coupled to Fluent (as one domain— with small additional of work). Completion of this task will create only known example of commercial CFD code with reactor physics.

10 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Blowup of Fluent model linked to RELAP5-3D © model

11 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Validation Underway Using Gas- Cooled Reactors as Basis Prismatic reactor is focus Working fluid: helium Collaborators: Fluent, General Atomics, and INEEL Fluent model of lower plenum * will couple with RELAP5-3D © model of balance-of-system. ________________ * Lower plenum CFD calculations provided by Fluent Corporation.

12 VHTR R&D Plan Workshop Corvallis, OR September 19-20, RELAP5-3D © coupled to enable detailed analysis of lower plenum flow patterns Core Upper Plenum Lower Plenum Balance Of Plant Fluent model RELAP5 model RELAP5 model

13 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Fluid Behavior in Lower Plenum Need: Preliminary evaluation of turbulent intensity and mixing characteristics likely to be present in lower plenum (LP) at rated condition. Use existing CFD model of LP with most representative turbulence model and perform preliminary evaluation of fluid behavior as function of location in LP. Helium gas entering domain around core support posts Helium gas exiting domain via Hot Duct Fluid Domain Core support post

14 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Validation of LP Flow Model Objective: The flow in the lower plenum of the NGNP will involve multiple jets entering from the core into a crossflow moving toward the exit duct and having to negotiate the presence of rows of support pillars. The modeling strategies (turbulence model, grid characteristics, time stepping, etc.) for simulating this complex turbulent flow must be validated.

15 VHTR R&D Plan Workshop Corvallis, OR September 19-20, RELAP5-3D © & Fluent Coupling Summary Fluent selected as collaborator—Fluent CFD may be capable of analyzing large fraction of required problems for gas-cooled and liquid metal advanced systems RELAP5-3D © & Fluent are coupled. The two codes will move forward time-step-by-time step after each code has converged. Coupling software has been extensively checked. Presently performing calculations to study mixing in prismatic lower plenum.

16 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Relationship of RELAP5-3D © to CFD Codes as a Group… RELAP5-3D © can be coupled with most, if not all, CFD codes. Bettis Atomic Power Lab has coupled CFX * with RELAP5-3D © using our Executive—consequently expertise to couple these codes for Gen IV use exists. STAR-CD has offered us access to their source code—however we haven’t had the resources to pursue their offer. No problems foreseen in coupling with non-commercial CFD codes. ______________________ * A variant of CFX—source code owned and modified by Bettis

17 VHTR R&D Plan Workshop Corvallis, OR September 19-20, Potential Non-Commercial CFD Candidates… LANL’s T-3 CFD codes. NPhase: Rensselaer Polytechnic Institute


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