STEP-BY-STEP INSTRUCTION FOR EXAMPLE 1
This example shows how to evaluate a double exposed PIV recording with EDPIV software. The image in Case D of PIV Challenge 2001 is used here as a sample recording. It is a double-exposure provided by the research group of Professor Adrian for a near-wall turbulent pip flow experiment. The measurement domain is 6-mm x 6-mm (beginning at the wall) in a 137-mm diameter pipe, and the flow was directed to right. The airflow was seeded with 1-micron olive oil droplets and illuminated with a pulsed YAG laser (~200 mJ/pulse). The particles were imaged with a Nikkor 80-mm f/5.6 Lens and recorded in a 4"x5" photographic film with resolution of 125 lines/mm. The time interval between the laser double pulses is 18 µs. The photographic PIV recording is digitized in size of 1024x1024 pixels. An evaluation procedure is suggested as follows.
Step 1: Load PIV recording
- Execute file “Edpiv.exe” - The start window is shown on the screen;
- Select menu “File \ Open recording 1”;
- Browse hard disks or CDs to find “…\ PIVsamples \ 1_DoubleExposure \ D001_1.bmp”;
- Select file “D001_1.bmp”, and then press “Open” button.
Step 2: Input imaging scale and time interval
- Click menu “Edit / Scale & time” in the start window to open dialogue box “Imaging scale / time interval”;
- Setup parameters as follows
- Press “OK” button to return to start window.
Step 3: Set up evaluation parameters
- Click menu “Edit / Evaluation settings” in the start window to open the “Evaluation settings” window;
- Set up parameters as follows
- Click menu “Image filter” to select
- Close “Evaluation settings” window.
Step 4: Evaluate the PIV recording
- Press button “Evaluation” in the start window;
- Click menu “Start” in “Evaluation” window;
- Answer “Yes” to question “Do you want to start an evaluation?”
- Wait until the evaluation is completed;
- Press button “OK” to close the dialogue box that notices the end of the evaluation;
Step 5: Save evaluation result
- Click menu “Edit \ Accept results \ valid + corrected” to accept valid and corrected displacement vectors;
- Click menu “File \ Save data” - Dialogue box “Save evaluation results” appears;
- Find a desired folder, type in a file name in the dialogue box;
- Press button “Save” to complete the saving procedure.
Step 6: Plot vector map
- Close EDPIV;
- Use TECPLOT to make plots.