Fluid Flow Simulation Software Nᐧ FLOW Tutorial Introduction Dam Break Simulation
Making A Simple Structure Using N-Flow - Let s make a basic model consists of simple plane and emitter. - Explanation of each items in progress is descried in Manual. - Items not mentioned in tutorial is default value that you don t need to input. 1. Material - You need to make attributes of material for structure first. Set frictional force, repulsive force and color. Input > Attribute > Material Name : Bottom Color : Gray... Close 2. Node - You can create node to use it for structure and emitter Input > Modeling > Node Input data in following order Start Point : 30, -15, 0 Start Point : -30, -15, 0 Start Point : -30, 15, 0 Start Point : 30, 15, 0...Add...Add...Add...Add... Close 1
3. Structure - You can make a structure. Let s make a simple plane. Input > Modeling > Structure Name: Bottom From: Plane Position Input: Node Material: Bottom Node ID: 1 1 Node ID: 2 1 Node ID: 3 1 Node ID: 4 1 2... Close 4. Emitter - Make an emitter (an entrance for supplying water) which generates particle. Input > Boundary Conditions > Emitter Name: Volume Width: 10 Height: 5 Velocity: 3 Position: Global Axis -29.5, 0, 10...Add... Close 2
5. Analysis - Do analysis with the model you create so far. First, you need to Save the file as name of Tutorial.nfb. And push Particle Run button to begin analysis. Input > Analysis > Particle Run If you want to stop analysis, click Stop! Analysis button. Input > Analysis > Stop! Analysis 3
Making A Dam Using N-Flow - Let s make a wall, dam and water gate structure. 1. Open Data File. - You need to Open the data file (Tutorial.nfb) you created in previous session. 2. Material. - Make attributes of material first. And then you are going to create a structure with that material. Input > Attribute > Material Name: Wall Color: Sky Blue Name: Gate Color: Purple... Close 4
3. Section. - Make plane components of structure to create the whole. Input > Attribute > Section Name: Pillar Type: Rectangular Center Type: Bottom H: 5 B: 1 Name: Wall Type: Rectangular Center Type: Bottom H: 10 B: 0.2... Close 5
4. Component. - Create a component which is going to be repeated. Input > Attribute > Component Name: Pillar Type: Line Section: Pillar Start Point: 0, 0, 0 End Point: 0, 1.5, 0 1 2... Close 5. Structure. - Create structures with section and component you made. Input > Modeling > Structure - Create the wall with part you made at 3. Section Name: Wall Form: Polyline Position Input: Node Materials: Wall Section: Wall Hide: Check Beta Angle: 180 Node ID: 1 1 Node ID: 2 1 Node ID: 3 1 Node ID: 4 1 2 6
- Create the pillars of dam by arranging components. Name: Pillar Form: Component Position Input: Global Axis Materials: Wall Section: Pillar Reference Point: -15, -15, 0 Reference Angle: 0, 0, 0 Repeat Num.: 4 Repeats Gap: 9.5 Direction Vector: 0, 1, 0 - Create the left side water gate with the parts you created at 3. Section Name: Gate_L Form: Line Position Input: Global Axis Materials: Gate Section: Pillar Beta Angle: 0 Start Point: -15, -13.5, 0 End Point: -15, -5.5, 0 7
- Create the central water gate with the parts you created at 3. Section Name: Gate_C Form: Line Position Input: Global Axis Materials: Gate Section: Pillar Beta Angle: 0 Start Point: -15, -4, 0 End Point: -15, 4, 0 - Create the right side water gate with the parts you created at 3. Section Name: Gate_R Form: Line Position Input: Global Axis Materials: Gate Section: Pillar Beta Angle: 0 Start Point: -15, 5.5, 0 End Point: -15, 13.5, 0...Close 8
6. Analysis - Perform analysis with the structure you have made so far. Click Particle Run to operate analysis. (It would be saved automatically even if you didn t save) Input > Analysis > Particle Run If you want to stop analysis, click Input > Analysis > Stop! Analysis For your information, you can boost up your analysis by enlarging particle s size. Input > Analysis > Stop! Analysis Particle Size: 0.3 or 0.4... OK 9
Simulation of Dam Break - You can move structure or can change the quantity of particle generated from emitter during analysis. - In this session, we are going to control the level of fluid and open the water gate of dam. 1. Simulation Input > Simulation > Simulation Name: Open 1. Structure Tab. - Set Gate_c to move upward by 90 from 31sec to 33sec from structure tab. Structure: Gate_C Position Input: Global Axis Rotate Center: Center of Structure Data Size: 2 Set Size Type Time Distance Rotate Center Rotate X Y Z X Y Z X Y Z Repeat Move 20 0 0 0 0 0 3 0-90 0 Shift 22 0 0 0 0 0 0 0 0 0.. Add1 2 Emitter Tab. - Set emitter to stop generating particle at 20sec from emitter tab. Emitter: Volume Type: Table Data Size: 1 Set Size Type Time Flow Rate Velocity Interval Repeat Velocity Change 23 0 0 0.. Add1 10
.. Add2 Close 3. Analysis Setting Result > Analysis > Analysis Setting Select simulation, set time for saving and set to close analysis after the time is over. Set to save particle, trajectory and measurement grid. Simulation : Open... OK 11
4. Analysis. - Perform analysis by click particle run (It would be saved automatically even if you didn t save) Input > Analysis > Particle Run If you want to stop simulation, click Input > Analysis > Stop! Analysis. 12
Importing CAD Data - In previous session, we used a modelling tool of N-Flow to make a dam. And to make more complicated structure, N-Flow can use CAD data by importing. 1. Material. - N-Flow imports CAD file per layer, 1 layer is transformed into 1 structure. And you can apply the material you made in advance to transformed structures when you import CAD file. Input > Attribute > Material Name: SIDE Color : Add Name: 가로등 Color : Add Streetlight Name: 깃대 Color : Add Flagpole Name: 깃발 Color : Add Flag Name: 인도 Color : Add Sidewalk Name: 주춧돌 Color : Add Foundation Stone Name: 차도 Color : Add Roadway Create 7 materials like above picture. 2. Cad Import Input > Modeling > CAD Import To import CAD file Bridge.dwg, click CAD import button and select it. 13
If you open file, you could see the dialog like below. Check the same parts as in the picture. Select Layer Name Material Type Materials Color Position Active Drain Hide 인도 재료 인도 차로 절대좌표 SIDE 재료 SIDE 차로 절대좌표 가로등 재료 가로등 차로 절대좌표 깃대 재료 깃대 차로 절대좌표 주춧돌 재료 주춧돌 차로 절대좌표 깃발 재료 깃발 차로 절대좌표 차로 재료 차로 차로 절대좌표 Then it creates a bridge. 14
3. Analysis - Perform analysis by click particle run (It would be saved automatically even if you didn t save) Input > Analysis > Particle Run If you want to stop simulation, click Input > Analysis > Stop! Analysis 를 클릭합니다. 15
Result (Various Settings of Rendering) - You can review the result of analyzed date. - 1. Analysis Setting Result > Analysis > Analysis Setting Select simulation, set time for saving and set to close analysis when the time is over. Set to save particle, trajectory and measurement grid. Simulation: Open Save Out: Check Start Time: 20 End Time: 50 Set End Solver: Auto save and exit Particle: Check Trajectory: Check Measurement Grid: Check... OK... Close 2. Running simulation. Input > Analysis > Particle Run 16
3. Reviewing the Saved Result Result > Option > Result Option 1. Particle 2. Trajectory 3. Velocity Check the result that you want to review and click Ok. And Click Result > Results > Play result. to play the 3-1. Particle 17
3-2. Trajectory 3-3. Vector 18