Computational Fluid Dynamics Air Flow through the Pipe with Orifice
CFD laboratory Prof. Dr.-Ing. Muris Torlak Anderson de Oliveira 00739606
displayed in the monitor. Loading the 3D model in the CFD program The 3D model “orifice. The imported 3D part appearance. In order to complete the 3D loading process the file was imported via “File Import Import Surface Mesh” as it is shown in the Figure 1.Target Simulate via STAR CCM+.x_t” was given and the simulation process inside STAR CCM+ started through “File New Simulation” and “Run Mode Serial”. Figure 1 – Importing the surface mesh Figure 2 – 3D part loaded in the program 2 . the air flow through a pipe with an orifice according to the given boundary conditions and provide the appropriate and requested analysis. from company CD-adapco. is illustrated the Figure 2.
the model was split by patches which. afterwards. it was applied a functionality to distinguish the color of the surfaces. Figure 3 – Split by patches Figure 4 – Color mode to distinguish the parts The Figure 5 illustrates the application of the color mode function. These steps are shown in the Figure 3 and Figure 4. Figure 5 – Application of the color mode functionality 3 .Splitting the model and distinguishing the surfaces After finishing the loading process. In addition. were used to define the boundary conditions on each surface.
Figure 6 – Meshing parameters definition The reference value for the base size was changed to 2mm as it is shown in the Figure 7 Figure 7 – Meshing base size changed to 2mm 4 .Meshing definition and creation Figure 6 demonstrates the meshing parameters which were applied. as follows: • Trimmer and • Prism Layer Mesh.
17. Converting mesh into finite volume representation in Region CDF Orifice .99 MB ---------------------------------------Assembling core mesh and prismatic mesh. Figure 8 – Mesh scene Below are some information about the mesh that was generated.60 MB Cells: 5041 Faces: 13234 Vertices: 6335 5 . Memory: 8. Extrusion mesh contains: • 1718 cells • 6179 faces • 7336 edges • 2876 vertices ---------------------------------------Prism Layer Extrusion Completed: CPU Time: 0.17. Memory: 4. Wall Time: 8. Wall Time: 0.Finally the mesh was created according to the parameters which were set-up above and the Figure 8 “Mesh Scene” illustrates the appearance of the part after meshing in the monitor.55.task 1 Volume Meshing Pipeline Completed: CPU Time: 8.55.
were introduced in the physics model.205 kg/m3 6 Figure 11 – Dynamic viscosity: 1. these properties are illustrated through Figure 10 and Figure 11. Figure 9 – Physics model settings The air properties. i.e. Figure 10 – Air density: 1. density and dynamic viscosity.845x10-5 Pa s .Selecting the physics model All the settings of the physics model were defined as it is shown in the Figure 9.
Applying the boundary conditions in the regions Regarding to the boundary conditions. inlet temperature: 20°C Figure 13. • • • • • inlet velocity: 3 m/s Figure 12. the following values were implemented in the model and it is shown by each figure respectively. static-pressure outlet at the downstream boundary: 0 Pa periodic side boundaries Figure 16. Figure 15 and Figure 12 – Inlet velocity: 3 m/s Figure 13 – Inlet temperature: 20°C 7 . orifice wall temperature: 300°C Figure 14.
Figure 14 – Orifice wall temperature: 300°C Figure 15 – Static-pressure outlet at the downstream boundary: 0 Pa Figure 16 – Periodic side boundaries 8 .
the simulation was performed and the following results were obtained: • • • • streamlines in the mid-plane along the pipe Figure 17 streamlines velocity Figure 18. • Figure 17 – Streamlines in the pipe mid-plane 9 . defining the boundary conditions. contour plots in radial plane inside the pipe: o velocity magnitude Figure 23. reattachment length – distance between the orifice plate and the wall point behind the orifice plate where the flow attaches to the wall Figure 19. o static pressure Figure 21. o residual history Figure 22. setting the physics and. least but not least. 2D plots: o axial velocity Figure 20.Running the simulation and post-processing After generating of the mesh. o axial velocity Figure 24 o pressure Figure 25 and o temperature Figure 26.
Figure 18 – Streamlines velocity in “z” axle direction Figure 19 – Reattachment length 10 .
3x10-3 Pa. 0.274904e-03 (Pa) position: (0.01268597260734075.4999790024471105E-4.117m where the pressure was 1. **cell probe entity: Walls 2 cellId: 550 field: Wall Shear Stress [k] value: 1. yielding to the reattachment length of 0.The length of the reattachment was taken through the wall shear stress plot in the “z” direction combined with picking the lowest pressure value. The message below was used to get the measurement. Figure 20 – Axial velocity plot 11 .11674378043616723) (m) Thus the pressure nearest to zero was found and its coordinate points. assumed as zero in this analysis. 1.
Figure 21 – Static pressure plot Figure 22 – Residual history plot 12 .
Figure 24 – Velocity magnitude Figure 23 – Velocity magnitude Figure 24 – Axial velocity 13 .
0200m from the inlet as it is illustrated in the Figure 26 and Figure 27. Their distances were 0.0145m and 0. o axial velocity Figure 24 o pressure Figure 25 and o temperature Figure 26.0145m Inlet 0. 0.o velocity: magnitude Figure 23. Figure 25 – Temperature Comparison between results applying different mesh types In order to compare the meshes it was created two section planes.02m Figure 26 – Planes section details Figure 27 – Planes section overview 14 . the first before and second one after the orifice.
i. • prism layer mesher and • base size 2mm Mesh definition: • polyhedral mesher. All the boundary conditions were kept the same. before the orifice Mesh definition: • trimmer. pressure and temperature. with respect to the mesh type.Two tables were built-up to show the differences between the two meshes in both planes. before and after the orifice. • prism layer mesher and • base size 5mm 15 . Table 1: Plane 1 – 0. • surface mesher. axial velocity.e.0145m.
• prism layer mesher and • base size 5mm 16 . • surface mesher.02m. • prism layer mesher and • base size 2mm Mesh definition: • polyhedral mesher. • prism layer mesher and • base size 2mm Mesh definition: • polyhedral mesher.0145m. before the orifice Mesh definition: • trimmer. • surface mesher.Table 1: Plane 1 – 0. after the orifice Mesh definition: • trimmer. • prism layer mesher and • base size 5mm Table 2: Plane 2 – 0.
it is recommended to perform further analysis. in the planes before and after the orifice. • prism layer mesher and • base size 2mm Mesh definition: • polyhedral mesher. comparing the results of the axial velocity and pressure. Regarding to the comparison of the temperature on planes and in the meshes. in order to verify whether the temperature on the wall could really achieve 235°C or not. • prism layer mesher and • base size 5mm Conclusion There were no relevant differences.02m. a multiphysic simulation would also be valuable to evaluate the influence of the temperature with respect to: • thermal expansion which could lead to increase the volume and • strength that could decrease depending of the material chosen. In addition to that. by an experienced professional. 17 . • surface mesher. after the orifice Mesh definition: • trimmer.Table 2: Plane 2 – 0.