 |
ACRi -- Analytic & Computational Research, Inc.
|
General FREEFORM Examples FREEFORM is the English-like conversational commands language that all ACRi software use to take input. These examples are provided for two distinct purposes:
Color and Case Coding Guideline: Note that FREEFORM is case-insensitive, and the input is in plain text format. However, to highlight the keywords and modifiers, UPPER case letters are often used. The colors are simply for illustrational purposes. These are: RED: keywords (first 4 letters of a word that starts at column 1) BLUE: modifiers (first 4 letters of a recognized word that comes after a keyword -- every keyword has a unique set of modifiers, as outlined in the users manual) AND variables (these are both default variables such as X -- distance in axial direction -- and user-defined variables such as pmon - phase of the moon -- as an example) GREEN: comments (start with "/" or "*" at column 1 or "$" or "!" at any column) See FREEFORM™ front page to read more about FREEFORM™ command syntax.
PROBLEM 1 Description The following FREEFORM™ commands illustrate the capabilities of ANSWER™ to dynamically define:
************************************************************************ TITLE SQUARE CAVITY PROBLEM WITH USER-DEFINED TRANSPORT & REACTION ************************************************************************ // This data set for ACRi Software ANSWER illustrates the use of // the FREEFORM command language to dynamically define: // >> New Field Variables, // >> New Transport Equations, and // >> Complex Reactions and Sources // ************************************************************************ / // The problem is set in the context of the classic Square Cavity // with a moving lid at the top. // // A new species call DOGS is defined on the fly which is governed by // a transport equation. The transport properties and boundary conditions // for DOGS are defined by simple commands. // // The distribution of DOGS is effected by the availability of MEAT // as a sinusoidal function of Time, and a 1st-order Arrhenius reaction // called KILLed. These are defined on-the-fly. // // MEAT = 2.0 * SIN ( 0.06886 * Time + 1. ) +2.0 // KILLed = -19.6 * exp(-937/T) DOGS^0.5 / // In addition in one part of the domain, the DOGS are regenerated as // as a function of U velocity if it is positive and eliminated if it is // negative. The function is defined as a arbitrary tabulated function ************************************************************************ / GRID NODEs BY 22 BY 22 ! Use structured mode of ANSWER / COORDINATE X RANGE 1 ! Auto gridding; range specified COORDINATE Y RANGE 1 ! Auto gridding; range specified / ***** Flow conditions WALL at all outer boundaries BOUNdary U: at boundary Y+, VALUE=1. ! Specify moving top wall LAMINAR flow VISCOSITY is 0.01 SET T (temperature) = 293.15 / ***** Define new variables on the fly ALLOCATe "DOGS- Members of Canine Family" ALLOCATe "MEAT- Food for Dogs" / ////////////////////////////////////////////////////////////////////// **** Define Transport equation for DOGS and its attributes ////////////////////////////////////////////////////////////////////// INITial value of DOGS = 10 PRANDtl Number for DOGS is 0.1 ! Boundary conditions for DOGS including a linear function at top BOUNdary X- (left) for DOGS: Value = 2 ! Fixed value BOUNdary X+ (right) for DOGS: FLUX = 0 ! No DOGS leave or enter BOUNdary Y- (bottom) for DOGS: FLUX = 1.E-4 ! dogs enter from bottom BOUNdary Y+ (top) for DOGS: VALUe = Linear function 2. +8. * X ////////////////////////////////////////////////////////////////////// // Define MEAT as sinusoidal function of TIME; make it source for DOGS ////////////////////////////////////////////////////////////////////// SET MEAT = 2. * SIN ( 0.06886 * Time + 1. ) +2. ALWAys SOURce for DOGS is LINEAR function: 0. +1. * MEAT per unit VOLUme ! Assume dogs die as a non-linear Arrhenius function of population ALLOCATE 'KILL- Killed from various causes' REACtion KILL DOGS Z0 = 19.6 TEMPerature_activation = 937 power = 0.5 SOURce REACTION type for DOGS LINEar -1. * KILL ! Assume in one subregion dogs die when U < 0 & are born when U > 0 SELECT subregion 5,5 to 7,7 SOURCE for DOGS for SELECted region is a TABLE of 3 sets in terms of U // U SOURCE -1 -0.01234 0. 0 1. 2.1234 ////////////////////////////////////////////////////////////////////// **** END of specification for DOGS' transport equation ////////////////////////////////////////////////////////////////////// REACtion default hydrocarbon OFF DIAGNOSTIC NODE print Time, U, V and DOGS AT (6,6) every 50 step CONVERGENCE REFErence U in LOCAL mode 1.E-6 / OUTPUT U DOGS, MEAT, KILL NARRow mode HISTORY of U DOGS MEAT and KILL with PLOT output on file "DOGS.HIS" HISTORY at (2,2) (5,5) (7,7) and (10,10) every 16 STEPS / SOLVE U V P & DOGS for 365 days in step of 0.1 END
PROBLEM 2 Description The following commands were used to set up and run a new 5 step methane combustion mechanism in the University of Washington jet stirred reactor. /-----------------------------------------------------------------/ TITLE Case K. COMBUSTION IN UW JSR - 5-STEP UW CH4/AIR MECH. /-----------------------------------------------------------------/ / ANSWER Input File / / Using UW 1-atm CH4-Air 5-Step Mechanism / 2-D Problem / / Reference: Nicol, D.G., Malte, P.C., Hamer, A.J., Roby, R.J., / Steele, R.C., 1998, "Development of a Five-Step / Global Methane Oxidation - NO Formation Mechanism / for Lean-Premixed Gas Turbine Combustion," to / appear in Transactions of ASME (Earlier version / of this work also in Western States/CI paper number / 97S-039). / /------------------------GRID SPECIFICATION-----------------------/ / 2-D Grid GRID 117 by 43 COORdinates X JIK 'x_jsr.grd' in FULL CYLIndrical COORdinates R JIK 'r_jsr.grd' in FULL CYLIndrical /----------------------DEFINE BOUNDARY REGIONS--------------------/ / Inlet Jet LOCAte ID=IN1 (1,1) (1,12) INLEt at X- ID=IN1 / Outlet Drain Hole SELEct (24,43) (30,43) OUTLet at R+ for the SELEcted subregion / Axis of Symmetry SYMMetry at Y- axis / Set Walls WALLs at undefined outer boundaries /------------------------CHEMICAL REACTIONS-----------------------/ / Set up combustion from scratch (i.e., turn off all the default / reaction details) REACtion OFF DEFAULT / Define molecular weights of the species GAS FU=16.0 CO=28.0 CO2=44.0 H2O=18.0 N2=28.0 O2=32.0 NO=30.0 /Allocate space for reaction rates, called R1, R2, R3, R4, R5 ALLOcate R1 ALLOcate R2 ALLOcate R3 ALLOcate R4 ALLOcate R5 / Define reaction rates (NOTE: FU = CH4) / CH4 + 1.5 O2 => CO + 2 H2O / 1.66E+15 = Pre-exponential (see reference) / 2.0643E+04 = Activation temp / 1.46 = Exponent for FU / 0.5217 = Exponent for O2 / 0.0 = Temp exponent / EBU = Want to specify EBU rate for this reaction / TEMP = Include this modifier because using activation / temperature (instead of activation energy) REACtion R1 FU O2 1.66E+15 2.0643E+04 1.460 0.5217 0.0 EBU TEMP / CO + 0.5 O2 => CO2 REACtion R2 CO O2 7.98E+14 1.1613E+04 1.6904 1.570 0.0 EBU TEMP / CO2 => CO + 0.5 O2 REACtion R3 CO2 2.23E+14 6.2281E+04 1.0 0.0 EBU TEMP / N2 + O2 => 2 NO REACtion R4 CO O2 8.83E+23 5.3369E+04 0.7211 4.0111 0.0 EBU TEMP / N2 + O2 => 2 NO REACtion R5 N2 O2 9.27E+14 6.8899E+04 1.0 0.5 -0.5 EBU TEMP / EBU coefficients for each mechanism EBU R1 FU 3.0 EBU R2 CO O2 3.0 1.75 EBU R3 CO2 3.0 EBU R4 N2 3.0 EBU R5 N2 3.0 /---EBU 3.0 1000 /---------------SOURCE TERMS FOR SPECIES DIFF EQ------------------/ / Define source terms for CH4, CO, and NO / CH4 source term SOURce REACtion type FU LINEar -1.0 * R1 / / CO source term ( 1.75 = CO/CH4; 0.6364 = CO/CO2 ) SOURce REACtion type CO LINEar +1.75 * R1 -1.0 * R2 +0.63636 * R3 / / NO source term ( 2.1429 = 2 * NO/N2 = 2 * NO/CO ) SOURce REACtion type NO LINEar +2.1429 * R4 +2.1429 * R5 / /------------ALGEBRAIC EXPRESSIONS FOR OTHER SPECIES--------------/ / / Algebraic equations for total H-atom (FH), total O-atom (FO), / CO2, H2O, O2, and N2 by atom balance. FF is total C-atom. SET ALWAys LINEar FH = 0.0 +1.0 * FF SET ALWAys LINEar FO = 0.2331 -0.2331 * FF SET ALWAys LINEar CO2 = 2.75 * FF -1.571 * CO -2.75 * FU + 0.0 SET ALWAys LINEar H2O = 2.75 * FH -2.75 * FU +0.0 SET ALWAys LINEar O2 = 1.0 * FO -0.571 * CO -0.727 * CO2 -0.889 * H2O -0.533 * NO + 0.0 SET ALWAys LINEar N2 = -1.0 * FU -1.0 * CO -1.0 * CO2 -1.0 * H2O -1.0 * NO -1.0 * O2 + 1.0 /------------------INITIAL AND BOUNDARY CONDITIONS----------------/ / / Walls of reactor are adiabatic ADIAbatic WALLS / Inlet Jet/Initial Conditions (Fuel-Air Equivalence Ratio = 1.1) SET U X- 78.4 ID=IN1 SET FU X- 0.06 ID=IN1 SET FF X- 0.06 ID=IN1 SET T 523.0 SET K 100.0 SET L 0.0004 / Initialize a 'hot' region to start combustion INITIAL T 2000.0 (2,2) (76,30) /-------------------FLUID PROPERTIES AND CONSTANTS----------------/ / Density calculated by Gas Law DENSity GAS / Specific heat and species enthalpies calculated by polynomial / expressions SPECific heat by NASA POLYnomial expressions /--------------------------SOLUTION OPTIONS-----------------------/ / Variable limit setting LIMIT FU 1.0E-20 1.0 LIMIT FF 1.0E-20 1.0 LIMIT H2O 1.0E-20 1.0 LIMIT CO2 1.0E-20 1.0 LIMIT O2 1.0E-20 1.0 LIMIT H2 1.0E-20 1.0 LIMIt CO 1.0E-20 1.0 LIMIt NO 1.0E-20 1.0 LIMIt T 523.0 4000.0 / / Relaxation Factors RELAxation U=0.3 V=0.3 W=0.3 P=0.3 K=0.3 E=0.3 T=0.3 FF=0.3 FU=0.3 CO=0.3 NO=0.3 / Monitor solution at (90,5) every 10 iterations DIAGnostic output for U, V, T, NO, FU, FF at (90,5) in every 1 steps /------------------------OPERATIONAL CONTROL----------------------/ / Convergence criteria - based on global residual CONVergence GLOBAL 1.E-9 1 SOLVE STEADY 5000 OUTPUT U V W P T K E L H FF FH FO FU CO O2 H2O CO2 NO N2 MU RHO SAVE U V W P T K E L H FF FH FO FU CO O2 H2O CO2 NO N2 MU RHO on file 'CaseK.sav' END
Related Links: |