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solving a conduction problem in FLUENT using UDF |
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April 13, 2010, 01:49 |
solving a conduction problem in FLUENT using UDF
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#1 |
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Avinash
Join Date: Apr 2010
Posts: 2
Rep Power: 0 |
Hi,
I am working on cooling of multi-core processors using core hopping. The way it works is - Say, I have a quad core processor. Initially I power "ON" one core. That core keeps running till it crosses a particular temperature threshold. Once, that temperature threshold is reached, I will turn that core "OFF" and turn "ON" another core in its place. Lets say, I do this for a period of 500 seconds. I created my model in ICEPAK. I simulated a "core" using a heat source. However, I need to write a UDF to perform the switching of cores based on temperature and, ICEPAK does not allow you to write UDFs. Thats the reason I had to learn to do this in FLUENT. I have no prior experience of working with FLUENT and I need to get this done immediately. I imported my model into FLUENT by reading in the case file generated by icepak and I did not find any meshing errors. I then wrote my UDF s to perform the switching but when I tried interpreting/compiling them, I found a host of errors that I couldn't resolve. I request you to kindly help me out. My UDFs are given as follows. I have commented them to try and make them as self-explanatory as possible. I have listed the errors after each UDF. The cores are labelled 1, 14, 5 and 7. What I am trying to simulate through these UDFs is that : Initially - Core 1 is powered ON. If the temperature of core 1 goes above 70 deg C, then turn it off and Turn ON core 14. Similarly, if core 14 goes above 0 deg C, turn ON core 5, if core 5 goes above 70 deg C, turn ON core 7 and if Core 7 goes above 70, go back to Core 1. I am posting just the UDFs for core 1 and core 14 as the rest are just repeats of the code for core 14 and have the same errors. 1.) #include"udf.h" /* function for giving power to core 1 */ DEFINE_PROFILE(core_1_power,t,i) { face_t f; face_t f1; real temp1; /* Check Temperature of Core 1 */ begin_f_loop(f,t) { temp1=F_T(f,t); } end_f_loop(f,t) while(temp1<343) { begin_f_loop(f,t) { F_PROFILE(f,t,i)=0.394527e+006; /* As long as temperature of core 1 is < 70 deg C,Keep it turned ON */ } end_f_loop(f,t) } /* end of while loop */ if(temp1>343) { begin_f_loop(f,t) { F_PROFILE(f,t,i)=0; /* If temperature of core 1 is > 70 deg C, turn it OFF */ } end_f_loop(f,t) Thread *t1=Lookup_Thread(domain,26); /* Get thread for core 14 */ begin_f_loop(f1,t1) { F_PROFILE(f1,t1,i)=0.394527e+006; /* Switch Core 14 ON instead of core 1 */ } end_f_loop(f1,t1) } else { begin_f_loop(f,t) { F_PROFILE(f,t,i)=0.394527e+006; /* Otherwise Keep Core 1 ON */ } end_f_loop(f,t) } } Errors : (37) : error C2275: 'Thread' : illegal use of this type as an expression (37) : error C2065: 't1' : undeclared identifier (37) : error C2065: 'domain' : undeclared identifier (37) : warning C4047: 'function' : 'Domain *' differs in levels of indirection from 'int' (37) : warning C4024: 'Lookup_Thread' : different types for formal and actual parameter 1 (39) : error C2065: 't1' : undeclared identifier (39) : error C2223: left of '->nelements' must point to struct/union (41) : error C2065: 't1' : undeclared identifier (41) : error C2223: left of '->storage' must point to struct/union 2. Code for Core 14 #include"udf.h" /* Function for assigning power to core 14 */ /* Core 14 will be turned ON only if Core 1 Exceeds 70 Deg C */ DEFINE_PROFILE(core_14_power,t,i) { face_t f; face_t f1; face_t f2; real temp1; real temp2; Thread *t1=Lookup_Thread(domain,16); /* Lookup Thread for core 1 */ begin_f_loop(f1,t1) { temp1=F_T(f1,t1); /* get temperature of core 1 */ } end_f_loop(f1,t1) while(temp1<343) { begin_f_loop(f,t) { F_PROFILE(f,t,i)=0; /* As long as core 1 is not > 70 deg C, core 14 remains turned OFF */ } end_f_loop(f,t) } /* End of while loop */ if(temp1>343) /* Provided Core 1 is > 70 Deg C */ { begin_f_loop(f,t) { temp2=F_T(f,t); /* Get Temperature of core 14 */ } end_f_loop(f,t) if(temp2<343) { begin_f_looop(f,t) { F_PROFILE(f,t,i)=0.394527e+006; /* If core 14 is < 70 Deg C (while core 1 is > 70 Deg C) turn ON core 14 and keep it ON for as long as it is below 70 Deg C */ } end_f_loop(f,t) } else { begin_f_loop(f,t) { F_PROFILE(f,t,i)=0; /* If temperature of core 14 is also > 70 Deg C, do NOT turn it ON */ } end_f_loop(f,t) Thread *t2=Lookup_Thread(domain,19); /* Lookup Thread for core 5 */ begin_f_loop(f2,t2) { F_PROFILE(f2,t2,i)=0.394527e+006; /* Turn ON core 5 */ } end_f_loop(f2,t2) } /* end of nested if-else loop */ else { begin_f_loop(f,t) { F_PROFILE(f,t,i)=0; /* If core 1 is not > 70 Deg C, then core 14 power is anyway zero */ } end_f_loop(f,t) } /* End of outer if-else loop */ } Errors: (16) : error C2065: 'domain' : undeclared identifier (16) : warning C4047: 'function' : 'Domain *' differs in levels of indirection from 'int' (16) : warning C4024: 'Lookup_Thread' : different types for formal and actual parameter 1 (45) : error C2143: syntax error : missing ';' before '{' (52) : error C2059: syntax error : 'else' (69) : error C2059: syntax error : 'else' (77) : error C2059: syntax error : '}' I apologize for the very long post and also if any of my errors are really trivial. I would appreciate any prompt help with this as I dont know of anybody here who has worked with UDF and also, I need to get it done immediately. Thank you very much. Regards, Avinash Raghu. Graduate Student, University of Texas at Arlington. |
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March 13, 2015, 02:02 |
Errors
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#2 |
Member
Baradwaj B S
Join Date: Jan 2015
Posts: 75
Rep Power: 11 |
Hi avinash,
As per my knowledge most your errors are typing mistakes. That is the reason why you are getting syntax errors. Try to go through how the basic syntax of C programming works. I had faced the same problem. And some variables like Thread, Domain, etc they are never defined but are being used in your program. Declare them and I think your program should work fine. Bharadwaj B S |
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