1 / 11

~0.5 m

1 of 11. A Microsegregation Model – Vaughan Voller, University of Minnesota. Process. REV. representative ½ arm space. solid. g. ~ 50 m m. ~5 mm. ~0.5 m. sub-grid model. Computational grid size. column. floor. building. 2 of 11. Solidification Modeling. Process. REV.

dshelley
Download Presentation

~0.5 m

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 1 of 11 A Microsegregation Model – Vaughan Voller, University of Minnesota Process REV representative ½ arm space solid g ~ 50 mm ~5 mm ~0.5 m sub-grid model Computational grid size column floor building

  2. 2 of 11 Solidification Modeling Process REV representative ½ arm space solid g ~ 50 mm ~5 mm ~0.5 m sub-grid model Computational grid size from computation Of these values need to extract -- -- --

  3. A C 3 of 11 Primary Solidification Solver g Transient mass balance g model of micro-segregation Iterative loop Cl T (will need under-relaxation) equilibrium

  4. Micro-segregation Model 4 of 11 liquid concentration due to macro-segregation alone new solid forms with lever rule on concentration transient mass balance gives liquid concentration Solute mass density after solidification Solute mass density before solidification q -– back-diffusion Solute mass density of new solid (lever) (1/s) Need an easy to use approximation For back-diffusion

  5. 5 of 11 Ohnaka The parameter Model --- Clyne and Kurz, parabolic growth solidification time m = 2.33 Coarsening Voller and Beckermann suggest

  6. 6 of 11 The Profile Model Wang and Beckermann solidification time parabolic growth proposed modification NOTE steeper profile at low liquid fraction Need to lag calculation one time step and ensure q >0 Coarsening Voller and Beckermann suggest

  7. 7 of 11 Constant Cooling of Binary-Eutectic Alloy With Initial Concentration C0 = 1 and Eutectic Concentration Ceut = 5, No Macro segregation , k= 0.1 Use 200 time steps and equally increment 1 < C < 5 Calculating the transient value of g from Remaining Liquid when C =5 is Eutectic Fraction Parameter or Profile Coarsening No Coarsening

  8. 8 of 11 Parabolic solid growth – No Second Phase Use 10,000 time steps and set g = t1/2 at each step C0 = 1, k = 0.13, a = 0.4 Use To calculate segregation ratio

  9. 9 of 11 Performance of Profile Model parabolic growth no second phase Prediction of segregation ratio in last liquid to solidify (fit exponential through last two time points) k =0.1 k =0.4

  10. Solidification Solver A C 10 of 11 Calculate Transient solute balance in arm space predict T Predict g predict Cl Two Models For Back Diffusion Profile Parameter A little more difficult to use Robust Easy to Use Possible Poor Performance at very low liquid fraction With this Ad-hoc correction Excellent performance at all ranges

  11. 11 of 11 I Have a BIG Computer Why DO I need an REV and a sub grid model solid ~ 50 mm ~5mm (about 106 nodes) Voller and Porte-Agel, JCP 179, 698-703 (2002 .5m 1000 20.6667 Year “Moore’s Law” Model Directly 2055 for tip Tip-interface scale current for REV of 5mm (about 1018 nodes)

More Related