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-pressure outlets µÈ£©£¬¾ùΪ``escape''±ß½çÌõ¼þ
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ͨÓöàÏàÁ÷Ä£ÐÍ£¨General Multiphase Models£©
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1. Ñ¡ÔñͨÓõĶàÏàÁ÷Ä£ÐÍ
VOF Ä£ÐÍÊʺÏÓÚ·Ö²ãµÄ»ò×ÔÓɱíÃæÁ÷£¬¶ømixture ºÍEulerianÄ£ÐÍÊʺÏÓÚÁ÷¶¯ÖÐÓÐÏà»ìºÏ»ò·ÖÀ룬»òÕß·ÖÉ¢ÏàµÄvolume fraction ³¬¹ý10%µÄÇéÐÎ,(Á÷¶¯ÖзÖÉ¢ÏàµÄvolume fraction СÓÚ»òµÈÓÚ10%ʱ¿ÉʹÓÃÀëÉ¢ÏàÄ£ÐÍ£©¡£
ΪÁËÔÚmixtureÄ£ÐͺÍEulerian Ä£ÐÍÖ®¼ä×÷³öÑ¡Ôñ£¬»¹Ó¦¿¼ÂÇÒÔϼ¸µã£º ¡ïÈç¹û·ÖÉ¢ÏàÓÐ×Å¿í¹ãµÄ·Ö²¼£¬mixture Ä£ÐÍÊÇ×î¿ÉÈ¡µÄ¡£Èç¹û·ÖÉ¢ÏàÖ»¼¯ÖÐÔÚÇøÓòµÄÒ»²¿·Ö£¬ÄãÓ¦µ±Ê¹ÓÃEulerian Ä£ÐÍ¡£
¡ïÈç¹ûÓ¦ÓÃÓÚÄãµÄϵͳµÄÏà¼äÒ·Á¦¹æÂÉÊÇ¿ÉÀûÓõģ¨either within FLUENT or through a user-defined function£©£¬Eulerian Ä£ÐÍͨ³£±Èmixture Ä£ÐÍÄܸø³ö¸ü¾«È·µÄ½á¹û¡£Èç¹ûÏà¼äµÄÒ·Á¦¹æÂɲ»ÖªµÀ»òÕßËüÃÇÓ¦ÓÃÓÚÄãµÄϵͳÊÇÓÐÒÉÎʵģ¬ mixture Ä£ÐÍ¿ÉÄÜÊǸüºÃµÄÑ¡Ôñ¡£
¡ïÈç¹ûÄãÏë½âÒ»¸öÐèÒª¼ÆË㸶³ö½ÏÉٵļòµ¥µÄÎÊÌ⣬mixture Ä£ÐÍ¿ÉÄÜÊǸüºÃµÄÑ¡Ôñ£¬ÒòΪËü±ÈEulerian Ä£ÐÍÒªÉÙ½âÒ»²¿·Ö·½³Ì¡£Èç¹û¾«¶È±È¼ÆË㸶³ö¸üÖØÒª£¬ Eulerian Ä£ÐÍÊǸüºÃµÄÑ¡Ôñ¡£µ«ÊÇÇë¼Çס£¬¸´ÔÓµÄEulerian Ä£ÐͱÈmixture Ä£ÐÍ µÄ¼ÆËãÎȶ¨ÐÔÒª²î¡£
2. VOF Ä£Ð͵ĸÅÊö¼°¾ÖÏÞ(Overview and Limitations of the VOF Model)
VOF Ä£ÐÍͨ¹ýÇó½âµ¥¶ÀµÄ¶¯Á¿·½³ÌºÍ´¦Àí´©¹ýÇøÓòµÄÿһÁ÷ÌåµÄvolume fraction À´Ä£ÄâÁ½ÖÖ»òÈýÖÖ²»ÄÜ»ìºÏµÄÁ÷Ìå¡£µäÐ͵ÄÓ¦ÓðüÀ¨Ô¤²â£¬jet breakup¡¢Á÷ÌåÖдóÅݵÄÔ˶¯£¨the motion of large bubbles in a liquid£©¡¢the motion of liquid after a dam break ºÍÆøÒº½çÃæµÄÎÈ̬ºÍ˲̬´¦Àí£¨the steady or transient tracking ofany liquid-gas interface£©¡£ ¾ÖÏÞ£¨limitations£©£º
ÏÂÃæµÄһЩÏÞÖÆÓ¦ÓÃÓÚFLUENT ÖеÄVOF Ä£ÐÍ£º
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¡ï±ØÐëʹÓÃsegregated solver. ¼´VOF Ä£ÐͲ»ÄÜÓÃÓÚcoupled solvers.
¡ïËùÓеĿØÖÆÈÝ»ý±ØÐë³äÂúµ¥Ò»Á÷ÌåÏà»òÕßÏàµÄÁªºÏ£»VOF Ä£ÐͲ»ÔÊÐíÔÚÄÇЩ¿ÕµÄÇøÓòÖÐûÓÐÈκÎÀàÐ͵ÄÁ÷Ìå´æÔÚ¡£ ¡ïÖ»ÓÐÒ»ÏàÊÇ¿ÉѹËõµÄ¡£
¡ïStreamwise periodic flow (either specified mass flow rate or specified pressure drop)cannot be modeled when the VOF model is used.
¡ïSpecies mixing and reacting flow cannot be modeled when the VOF model is used. ¡ï´óÎÐÄ£ÄâÎÉÁ÷Ä£ÐͲ»ÄÜÓÃÓÚVOF Ä£ÐÍ¡£
¡ï¶þ½×ÒþʽµÄtime-stepping ¹«Ê½²»ÄÜÓÃÓÚVOF Ä£ÐÍ¡£ ¡ïVOF Ä£ÐͲ»ÄÜÓÃÓÚÎÞÕ³Á÷¡£
¡ïThe shell conduction model for walls cannot be used with the VOF model.
ÎÈ̬ºÍ˲̬µÄVOF ¼ÆËã
ÔÚFLUENT ÖÐVOF ¹«Ê½Í¨³£ÓÃÓÚ¼ÆËãʱ¼äÒÀÀµ½â£¬µ«ÊǶÔÓÚÖ»¹ØÐÄÎÈ̬½âµÄÎÊÌ⣬ËüÒ²¿ÉÒÔÖ´ÐÐÎÈ̬¼ÆËã¡£ÎÈ̬VOF ¼ÆËãÊÇÃô¸ÐµÄÖ»Óе±ÄãµÄ½âÊǶÀÁ¢ÓÚ³õʼʱ¼ä²¢ÇÒ¶ÔÓÚµ¥ÏàÓÐÃ÷ÏÔµÄÁ÷Èë±ß½ç¡£ÀýÈ磬ÓÉÓÚÔÚÐýתµÄ±×ÓÖÐ×ÔÓɱíÃæµÄÐÎ×´ÒÀÀµÓÚÁ÷ÌåµÄ³õʼˮƽ£¬ÕâÑùµÄÎÊÌâ±ØÐëʹÓÃtime-dependent ¹«Ê½¡£ÁíÒ»·½Ã棬ÇþµÀÄÚ¶¥²¿ÓÐ¿ÕÆøµÄË®µÄÁ÷¶¯ºÍ·ÖÀëµÄ¿ÕÆøÈë¿Ú¿ÉÒÔ²ÉÓÃsteady-state ¹«Ê½Çó½â¡£
3. Mixture Ä£Ð͵ĸÅÊöºÍ¾ÖÏÞ(Overview and Limitations of the Mixture Model)
»ìºÏÄ£ÐÍÊÇÒ»ÖÖ¼ò»¯µÄ¶àÏàÁ÷Ä£ÐÍ£¬ËüÓÃÓÚÄ£Äâ¸÷ÏàÓв»Í¬ËٶȵĶàÏàÁ÷£¬µ«ÊǼٶ¨ÁËÔڶ̿ռä³ß¶ÈÉϾֲ¿µÄƽºâ¡£ÏàÖ®¼äµÄñîºÏÓ¦µ±ÊǺÜÇ¿µÄ¡£ËüÒ²ÓÃÓÚÄ£ÄâÓÐÇ¿ÁÒñîºÏµÄ¸÷ÏòͬÐÔ¶àÏàÁ÷ºÍ¸÷ÏàÒÔÏàͬËÙ¶ÈÔ˶¯µÄ¶àÏàÁ÷¡£
»ìºÏÄ£ÐÍ¿ÉÒÔÄ£Äân Ïࣨfluid or particulate£©Í¨¹ýÇó½â»ìºÏÏàµÄ¶¯Á¿¡¢Á¬ÐøÐÔºÍÄÜÁ¿·½³Ì£¬µÚ¶þÏàµÄvolume fraction ·½³Ì£¬ÒÔ¼°Ïà¶ÔËٶȵĴúÊý±íʾ¡£µäÐ͵ÄÓ¦ÓðüÀ¨³Á½µ£¨sedimentation£©£¬Ðý·ç·ÖÀëÆ÷£¨cyclone separators£©£¬particle-laden flow with low loading,ÒÔ¼°ÆøÏàÈÝ»ýÂʺܵ͵ÄÅÝ×´Á÷¡£
»ìºÏÄ£ÐÍÊÇEulerian Ä£ÐÍÔÚ¼¸ÖÖÇéÐÎϵĺܺÃÌæ´ú¡£µ±´æÔÚ´ó·¶Î§µÄ¿ÅÁ£Ïà·Ö²¼»òÕß½çÃæµÄ¹æÂÉδ֪»òÕßËüÃǵĿɿ¿ÐÔÓÐÒÉÎÊʱ£¬ÍêÉÆµÄ¶àÏàÁ÷Ä£ÐÍÊDz»ÇÐʵ¿ÉÐеġ£µ±Çó½â±äÁ¿µÄ¸öÊýСÓÚÍêÉÆµÄ¶àÏàÁ÷Ä£ÐÍʱ£¬Ïó»ìºÏÄ£ÐÍÕâÑù¼òµ¥µÄÄ£ÐÍÄܺÍÍêÉÆµÄ¶àÏàÁ÷Ä£ÐÍÒ»ÑùÈ¡µÃºÃµÄ½á¹û¡£ ¾ÖÏÞÐÔ£¨limitation£©
ÏÂÃæµÄ¾ÖÏÞÓ¦ÓÃÓÚ»ìºÏÄ£ÐÍÔÚFLUENT ÖУº
¡ï±ØÐëʹÓÃsegregated solver.¼´»ìºÏÄ£ÐͲ»ÊʺÏÓÚÈκÎcoupled solver. ¡ïÖ»ÓÐÒ»ÏàÊÇ¿ÉѹËõµÄ¡£
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¡ïStreamwise periodic flow (either specified mass flow rate or specified pressure drop)cannot be modeled when the mixture model is used.
¡ïSpecies mixing and reacting flow cannot be modeled when the mixture model is used.
¡ïSolidification and melting cannot be modeled in conjunction with the mixture model.
¡ï´óÎÐÎÉÁ÷Ä£ÐͲ»ÄÜʹÓÃÔÚ»ìºÏÄ£ÐÍÖС£
¡ïThe second-order implicit time-stepping formulation cannot be used with the mixturemodel.
¡ï»ìºÏÄ£ÐͲ»ÄÜÓÃÓÚÎÞÕ³Á÷¡£
¡ïThe shell conduction model for walls cannot be used with the mixture model
4. Eulerian Ä£Ð͵ĸÅÊöºÍ¾ÖÏÞÐÔ£¨Overview and Limitation of the Eulerian Model£©
ÔÚFLUENT ÖеĿÉÒÔÄ£Äâ¶àÏà·ÖÀëÁ÷£¬¼°Ïà¼äµÄÏ໥×÷Óá£Ïà¿ÉÒÔÊÇÒºÌå¡¢ÆøÌå¡¢¹ÌÌåµÄ¼¸ºõÊÇÈÎÒâµÄÁªºÏ¡£Eulerian ´¦ÀíÓÃÓÚÿһÏ࣬Ïà±È֮ϣ¬Eulerian-Lagrangian ´¦ÀíÓÃÓÚÀëÉ¢ÏàÄ£ÐÍ¡£
²ÉÓÃEulerian Ä£ÐÍ£¬µÚ¶þÏàµÄÊýÁ¿½ö½öÒòΪÄÚ´æÒªÇóºÍÊÕÁ²ÐÐΪ¶øÊܵ½ÏÞÖÆ¡£Ö»ÒªÓÐ×ã¹»µÄÄڴ棬ÈκÎÊýÁ¿µÄµÚ¶þÏà¶¼¿ÉÒÔÄ£Ä⡣Ȼ¶ø£¬¶ÔÓÚ¸´ÔӵĶàÏàÁ÷Á÷¶¯£¬Äã»á·¢ÏÖÄãµÄ½âÓÉÓÚÊÕÁ²ÐÔ¶øÊܵ½ÏÞÖÆ¡£
FLUENT ÖеÄEulerian ¶àÏàÁ÷Ä£ÐͲ»Í¬ÓÚFLUENT4 ÖеÄEluerian Ä£ÐÍ£¬ÔÚFLUENT4ÖÐÒº-ÒººÍÒº-¹Ì£¨granular£©¶àÏàÁ÷¶¯Ã»ÓÐÈ«¾ÖµÄ²î±ð¡£¿ÅÁ£Á÷ÊÇÒ»ÖÖ¼òµ¥µÄÁ÷¶¯£¬ËüÉæ¼°µ½ÖÁÉÙÓÐÒ»Ïà±»Ö¸¶¨Îª¿ÅÁ£Ïà¡£ FLUENT ½âÊÇ»ùÓÚÒÔÏµģº ¡ïµ¥Ò»µÄѹÁ¦ÊDZ»¸÷Ï๲ÏíµÄ¡£ ¡ï¶¯Á¿ºÍÁ¬ÐøÐÔ·½³ÌÊǶÔÿһÏàÇó½â¡£ ¡ïÏÂÃæµÄ²ÎÊý¶Ô¿ÅÁ£ÏàÊÇÓÐЧµÄ£º
£¨1£©¿ÅÁ£Î¶ȣ¨¹ÌÌ岨¶¯µÄÄÜÁ¿£©ÊǶÔÿһ¹ÌÌåÏà¼ÆËãµÄ¡£ÕâÊÇ»ùÓÚ´úÊý¹ØÏµµÄ¡£
£¨2£©¹ÌÌåÏàµÄ¼ôÇкͿÉÊÓÕ³ÐÔÊǰѷÖ×ÓÔ˶¯ÂÛÓÃÓÚ¿ÅÁ£Á÷¶ø»ñµÃµÄ¡£Ä¦²ÁÕ³ÐÔÒ²ÊÇÓÐЧµÄ¡£
¡ï¼¸Ïà¼äµÄÒ·Á¦ÏµÊýº¯ÊýÊÇÓÐЧµÄ£¬ËüÃÇÊʺÏÓÚ²»Í¬ÀàÐ͵ĶàÏàÁ÷ϵ¡££¨ÄãÒ²¿ÉÒÔͨ¹ýÓû§¶¨Ò庯ÊýÐÞ¸ÄÏà¼äµÄÒ·Á¦ÏµÊý£¬as described in the separate UDFManual£©¡£
¡ïËùÓеĦÊ?¦ÅÎÉÁ÷Ä£ÐͶ¼ÊÇÓÐЧµÄ£¬¿ÉÒÔÓÃÓÚËùÓÐÏà»òÕß»ìºÏÏà¡£ ¾ÖÏÞÐÔ£¨Limitations£©£º
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³ýÁËÒÔϵÄÏÞÖÆÍ⣬ÔÚFLUENT ÖÐËùÓÐÆäËûµÄ¿ÉÀûÓÃÌØÐÔ¶¼¿ÉÒÔÔÚEulerian ¶àÏàÁ÷Ä£ÐÍÖÐʹÓãº
¡ïÖ»ÓЦÊ?¦ÅÄ£ÐÍÄÜÓÃÓÚÎÉÁ÷¡£
¡ï¿ÅÁ£¸ú×Ù£¨Ê¹ÓÃLagrangian ·ÖÉ¢ÏàÄ£ÐÍ£©½öÓëÖ÷ÏàÏ໥×÷Óá£
¡ïStreamwise periodic flow (either specified mass flow rate or specified pressure drop)cannot be modeled when the Eulerian model is used. ¡ïѹËõÁ÷¶¯ÊDz»ÔÊÐíµÄ¡£ ¡ïÎÞÕ³Á÷ÊDz»ÔÊÐíµÄ¡£
¡ïThe second-order implicit time-stepping formulation cannot be used with the Eulerianmodel.
¡ïSpecies transport and reactions are not allowed. ¡ïHeat transfer cannot be modeled.
¡ïThe only type of mass transfer between phases that is allowed is cavitation;evaporation, condensation, etc. are not allowed.
¶þ. ÉèÖÃÒ»°ãµÄ¶àÏàÁ÷ÎÊÌ⣨Setting Up a General Multiphase Problem£©
Õⲿ·ÖÌṩÁËʹÓÃVOF Ä£ÐÍ£¬»ìºÏÄ£ÐͺÍÅ·À¶àÏàÁ÷Ä£Ð͵ÄÓ÷¨ºÍÖ¸ÄÏ¡£ 1£®Ê¹ÓÃÒ»°ã¶àÏàÁ÷Ä£Ð͵IJ½Ö裨Steps for Using the General Multiphase Models£©
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£¨2£©´Ó²ÄÁÏ¿âÖи´ÖÆÃèÊöÿÏàµÄ²ÄÁÏ¡£ Define Materials...
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£¨3£©¶¨ÒåÏָ࣬¶¨Ïà¼äµÄÏ໥×÷Óã¨interaction£©(ÀýÈ磬ʹÓÃOVF Ä£ÐÍʱµÄ±íÃæÕÅÁ¦£¨surfacetension£©£¬Ê¹ÓûìºÏÄ£ÐÍʱµÄ»¬Á÷ËÙ¶È£¬Ê¹ÓÃÅ·ÀÄ£ÐÍʱµÄdrag functions) Define Phases...
£¨4£©(½ö¶ÔÅ·ÀÄ£ÐÍ)Èç¹ûÁ÷¶¯ÊÇÎÉÁ÷£¬¶¨Òå¶àÏàÎÉÁ÷Ä£ÐÍ¡£ Define Models Viscous...
£¨5£©Èç¹ûÌå»ýÁ¦´æÔÚ£¬turn on gravity and specify the gravitational acceleration. Define Operating Conditions...
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