Hi all, I am doing flow analysis in an engine cylinder with moving piston and valves using FLUENT6.1. I will be very thankful if you read the warning message attached below and feed me back with your help. Thank you in advance.

******* The message ***********

/define/models/dynamic-mesh-controls> position-starting-mesh Start Crank Angle (deg) [0] 30 Updating mesh position ... Done

Subdividing mesh layers

Warning: multiple subdivision required on zone 13. Warning: multiple subdivision required on zone 21.. Done

Remeshing cell zone cylinder-inter (id = 30)

remeshing face zone def-cyl (id = 22) with length scale = 2.50000e-04 remeshing face zone wa-5 (id = 25) with length scale = 2.50000e-04 remeshing face zone wa-7 (id = 27) with length scale = 2.50000e-04 remeshing face zone wa-9 (id = 26) with length scale = 2.50000e-04 remeshing face zone wa-11 (id = 28) with length scale = 2.50000e-04

Error: fluent.6.1.18 received a fatal signal (BUS ERROR). Error Object: #f

WARNING: non-positive volumes exist.

Hi sir, I suggest u go for AVL for ICE simulation, thats really make yr life easy. I had come across plenty of problems when do the simulation in fluent 6.1. By the way u can only do the flow analysis but for combustion, there is a problem. I guess fluent 6.1 dont have the spark ignition module for u. only 6.2 hav it. if possible go for AVL. i m seeking the AVL training as well. if u can found it let me know. thanks.

regards, Ray

hi, Mahrous. now i am also doing the i.c.e model. I can use this command successfully to remash. I think mybe your mash grid is not good enough. BTW, i have an other problem. i don't know how to define the motion of the valves. As the user's guide said, I type the profile"((ex-valve 5 point) (angle 0 180 270 360 720) (lift 0.05 0.05 1.8 0.05 0.05)) ((in-valve 5 point) (angle 0 355 440 540 720) (lift 0.05 0.05 2.0 0.05 0.05))" in. But, the massage shows"error:eval:nobound varibles" I don't know how to solve this. Hope you can help me.

Hi Handou, Thanks for your response. Regarding your inquiry about the valve profiles, I have defined them with different profiles. Attached is a copy of these profiles and it is OK with my model. Have you scaled your grid with grid/scale command in order to have the same unit as that of the valve profiles? Can you please let me know how you get the various regions defined in both Gambit and Fluent (dynamic mesh)? What is the meant by layering zones over piston and valves? I have defined them as separate interiors and mesh them by quadrilateral cells. Also what is the meant by remeshing zone (for the chamber zone)? I think it is a zone that may be meshed by triangular cells, isn't it? When I apply the command (define/models/dynamic-mesh-controls/position-starting-mesh) in the console Window and then display the grid, it seems that there is no change in the cylinder mesh zone (it is not remeshed). Can you please send me your example model (case and mesh files) for checking. I'm looking forward to reading from you. Regards ----------------------------------------------------------- (in-valve 24 point) (angle 6 7 12 13 15 20 25 30 35 40 45 47 50 55 60 65 70 75 80 85 90 95 97 100 ) (lift 0 0.3e-4 1e-4 4e-4 6e-4 8e-4 10e-4 12e-4 14.6e-4 20e-4 20e-4 20e-4 19e-4 17e-4 15e-4 13e-4 10e-4 8e-4 6.3e-4 4.8e-4 3e-4 1.2e-4 0.2e-4 .1e-4 )

((ex-valve 24 point) (angle 480 485 490 495 500 505 510 515 520 530 540 550 560 570 580 590 595 600 605 610 615 620 625 630 ) (lift 0 0.3e-4 1e-4 4e-4 6e-4 8e-4 10e-4 12e-4 14.6e-4 20e-4 20e-4 20e-4 19e-4 17e-4 15e-4 13e-4 10e-4 8e-4 6.3e-4 4.8e-4 3e-4 1.2e-4 0.2e-4 .1e-4 ) -----------------------------------------------------------

hello. i just did as FLUENT user guide chapter 9 said. i devide the CAD four parts: pipe, valve, chamber,pistion. Mesh valve&pistion by quadrilateral cells and pipe&chamber by triangular cells. But,before you mesh , you should first connect the overlap faces between the different parts. Now, i can't deal with the slide interface. When i preview the mesh motion, there will be error.

Dear friends, Remeshing is applicable for triangular cells only. Layering for quadrilateral cells.In the region of piston motion, you have to go for remeshing only, and not layering.

Many thanks Thomas. Do you mean that we shall define the chamber cell zone as a remeshing zone (not remeshing + layering)? Sir, do you know how to define the sliding interface zones (interface zones 1 and 2) and how to get the edges of the in/out ports of these zones remeshed as discussed in page 9-75 of FLUENT6.1 user guide although they are constituting parts of the layering zones above valves?

dear friend,

When you define layering and remeshing in in cylinder modelling,the hexahedral zones get automatically layered and tetrahedral get remeshed.Inside the chamber you can can create two zones and mesh region away from head hexahedral and near to head tetrahedral.Enable layering and remeshing.When piston moves hexahedral cells will be layered and tetrahedral layered.You can mesh the entire zone with tetrahedral also.Then only remeshing takes place.But given a choice of remeshing and layering, i will go for layering.Then about sliding meshes, one tutorial is available...bye

Hi Thomas, Thanks again. Can you please tell me how can I access this tutorial? I have the FLUENT6.1 documentation CD but here is no tutorial concerned with engine cylinder modeling. Regards