NESC9553 HYDRA-2.

1. NAME OR DESIGNATION OF PROGRAM:  HYDRA-2.

3. DESCRIPTION OF PROGRAM OR FUNCTION

HYDRA2 is a hydrothermal computer code capable of three-dimensional analysis of coupled conduction, convection, and thermal radiation problems. HYDRA2 is especially appropriate for simulating the steady-state performance of spent fuel storage systems. Several automated methods are available to model radiation transfer within enclosures and from fuel rod to fuel rod. HYDRA2 provides a finite-difference solution in Cartesian coordinates to the governing equations of mass, momentum and energy. A cylindrical coordinate system may also be used to enclose the Cartesian coordinate system. This exterior coordinate system is useful for modeling cylindrical cask bodies. The difference equations for conservation of momentum incorporate directional porosities and permeabilities that are available to model solid structures whose dimensions may be smaller than the computational mesh. The equation for conservation of energy permits  modeling of orthotropic physical properties and film resistances. When both coordinate systems are invoked, the code will automatically align the two systems and enforce conservation of energy at their interface.

4. METHOD OF SOLUTION

An implicit solution algorithm is used for both the momentum and energy equations to ease time-step limitations and  stability requirements. The time-dependent conservation equation of  energy with convection and heat sources is the basis for calculating temperature fields. A control-volume formulation is used to derive the algebraic equations from the basic differential equations.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

HYDRA2 does not provide a turbulence model to represent subgrid scale motion of the  fluid. Therefore, the Reynolds/Rayleigh numbers realized in the simulation must be sufficiently low so that all the scales of motion are resolved by the computational grid. Other limitations include no mass inflow/outflow boundary conditions and planar or two-dimensional cavity radiation heat transfer.

6. TYPICAL RUNNING TIME:

The test case has been run by NEA-DB on a CRAY-XMP/2800 computer. Despite some discrepancies with the original results, which still require clarification, the program has been released for distribution. Execution of the test case required 187 seconds of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS

HYDRA2, an enhanced version of HYDRA1, is a member of the HYDRA family of general-purpose codes collectively capable of transient three-dimensional analysis of coupled conduction, convection, and radiation problems.

10. REFERENCES:

- R.A. McCann :
  HYDRA-II: A Hydrothermal Analysis Computer Code
  Equations and Numerics
  Volume I, PNL-6206 Vol. I (April 1987)
- R.A. McCann, P.S. Lowery and D.L. Lessor :
  HYDRA II: A Hydrothermal Analysis Computer Code
  Volume II, User's Manual, PNL-6206
  Vol. II (September 1987)
- R.A. McCann and P.S. Lowery :
  HYDRA-II: A Hydrothermal Analysis Computer Code
  Volume III, Verification/Validation Assessments
  PNL-6206, Vol. III (October 1987)
- P. Johnson :
  HYDRA2 Tape Description
  NESC Note 88-45 (February 11, 1988)

11. MACHINE REQUIREMENTS:

Job size on a CRAY-XMP/2800 is 311,808 words.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  CTSS.

COS 1.5 (CRAY-XMP/2800) with compiler CFT 1.14.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS: , R.A. McCann, Pacific Northwest Laboratory

File name	File description	Records
NESC9553_01.001	Information file	83
NESC9553_01.002	JCL and control information	26
NESC9553_01.003	HYDRA-2 source program	7604
NESC9553_01.004	Sample problem input	613
NESC9553_01.005	Sample problem output	1866
NESC9553_01.006	Differences between the sample outputs	93