Application of the ASAP Technique in the Geophysical and Industrial Scales:

a Comparison with BFC

Lombard, E., Palacio, Rodriguez, A., Salinas, M., Vicente, W.

Engineering Institute of the UNAM, Mexicoap. post. 70-472, Coyoacan 04510, Mexico D.F.

PHOENICS User’s ConferenceAustralia, May 2004

Calculations for two very different scale situations:

1) A geophysical case represented by hydrodynamics in

a lake 2) An industrial facility represented by air flow in a

spillwater aerator

Two different approaches:

1) Body fitted coordinates2) Arbitrary Source Allocation Procedure Comparisons between the two models considering a

qualitative and quantitative point of view analyzing the flow patterns and the distribution of a scalar parameter.

INTRODUCTION

U ρ Cτ = ad210

) - (1 = t max

)41

( |u| h 0.4 = *2

1 = max

LAKE

Bathymetry of the lake

BFC Grid

ASAP Grid

Surface velocity distribution, BFC

Surface velocity distribution, ASAP

Bottom velocity distribution, BFC

Bottom velocity distribution, ASAP

ghPKkFr /K 321

AERATOR

Spllwater aerator

BFC Grid ASAP Grid

Air velocity at bottom of spillway, BFC

Air velocity at bottom of spillway, ASAP

Beta distribution at bottom of spillway, BFC

Beta distribution at bottom of spillway, ASAP

CONCLUSIONS

•Considering a qualitative and quantitative point of view, both approaches show very much similitude in the results obtained when analyzing the flow patterns and the distribution of a scalar parameter.

• ASAP requires a very moderate relaxation for velocities and no relaxation for the pressure, while the BFC computations require stronger relaxation for velocities, and for cases like the ones here presented a heavy linear relaxation for the pressure with values oscillating between 2 and 3.

• An overall preliminary analysis of the cases here presented, seem to indicate the calculations using the ASAP technique present more advantages when compared with the BFC approach:It allows to represent the domain in a more easy way by just defining the geometry with an autocad file and then simply assigning the desired grid refinement.Convergence is much easily attained.The results obtained do not suffer from grid generation problems, as for the BFC cases where the grid presents very skewed cells.

FINFIN