Thank you for stopping by.
I am recently working on a brain artery ica. Its diameter is in mm from somvascular measurements as it should be. The reading is about 4.3mm and I am wondering whether simvascular will run the simulation in MGS due to this reading. I was about to put every other parameters in CGS and suddenly this thought struck me.
Would like to look forward for reply!
Thanks always!
CGS and MGS units
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Adam Updegrove
- Posts: 236
- Joined: Fri Aug 30, 2013 4:11 pm
Re: CGS and MGS units
Hi Taehak,
You will need to make sure that the boundary conditions and fluid parameters (viscosity, density) are consistent with the units of your model. SimVascular will not do this automatically.
Thanks!
SimVascular Development Team
You will need to make sure that the boundary conditions and fluid parameters (viscosity, density) are consistent with the units of your model. SimVascular will not do this automatically.
Thanks!
SimVascular Development Team
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Taehak Kang
- Posts: 39
- Joined: Thu Jun 22, 2017 7:03 pm
Re: CGS and MGS units
So is it a yes or no? Does simvascular run in mgs when the photo image readings(such as volume and length, etc) are in mm?
I got all parameters in cgs. Working on an ICA.
viscosity:1.06
density:0.04
inlet:pulsatile, 3-10cc/s, 1s period/ wormsley
outlet:windkessel, RCR units: R,Rd=dynes*s/cm^5, C=cm^5/dynes /// values: 5393 0.0000116 54327 and all in similar style (C value can go to E-6)
time step:0.005
total time steps: 200
set fourier modes:10, points 20.
time construction : 4
time restarts : 10
however I was curious whether the image pixel size matters in simulation and calculation. when I measured the diameter of a vessel, it was 4.31mm and the area shown was like 4.21 when I clicked the cap. So my point is, does simvascular calculate the area of a vessel in mm when the pixel size is in mm? and is there any defects in the data I put above? I am not an expert in this field so I am really sure about them...
3 inlets(ICA,BA) and 8 outlets(all around CoW) and all arteries connected to each other just like normal CoW.
it seem I always get weird pressure/velocity values(like 6000Pa and 10cm/s where it should be 16000Pa and 50cm/s)! I got all values mostly from papers and I have went through like 30 or more of them I guess.. I am quite desperate haha..
I got all parameters in cgs. Working on an ICA.
viscosity:1.06
density:0.04
inlet:pulsatile, 3-10cc/s, 1s period/ wormsley
outlet:windkessel, RCR units: R,Rd=dynes*s/cm^5, C=cm^5/dynes /// values: 5393 0.0000116 54327 and all in similar style (C value can go to E-6)
time step:0.005
total time steps: 200
set fourier modes:10, points 20.
time construction : 4
time restarts : 10
however I was curious whether the image pixel size matters in simulation and calculation. when I measured the diameter of a vessel, it was 4.31mm and the area shown was like 4.21 when I clicked the cap. So my point is, does simvascular calculate the area of a vessel in mm when the pixel size is in mm? and is there any defects in the data I put above? I am not an expert in this field so I am really sure about them...
3 inlets(ICA,BA) and 8 outlets(all around CoW) and all arteries connected to each other just like normal CoW.
it seem I always get weird pressure/velocity values(like 6000Pa and 10cm/s where it should be 16000Pa and 50cm/s)! I got all values mostly from papers and I have went through like 30 or more of them I guess.. I am quite desperate haha..
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Hongzhi Lan
- Posts: 125
- Joined: Mon Aug 04, 2014 3:55 pm
Re: CGS and MGS units
Hi Taehak,
Since we create a model based on the patient's images, so the units should be same. In another word,
If you create a model based on an image in mm unit, the model is in mm.
If you create a model based on an image in cm unit, the model is in cm.
After the model is created, we create a mesh and run simulations just based on the model, there is nothing to do with the image any more.
Hongzhi
SimVascular Development Team
Since we create a model based on the patient's images, so the units should be same. In another word,
If you create a model based on an image in mm unit, the model is in mm.
If you create a model based on an image in cm unit, the model is in cm.
After the model is created, we create a mesh and run simulations just based on the model, there is nothing to do with the image any more.
Hongzhi
SimVascular Development Team
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Taehak Kang
- Posts: 39
- Joined: Thu Jun 22, 2017 7:03 pm
Re: CGS and MGS units
OH..
then if I create a model based on mm size image, the model is in mm
and the simulation parameters should also be in mm?
then cc/s should go mm^3/s and RCR value units should also be in mm^5/dynes and so on?
sorry it seems repeating but I really need confirmation...
then if I create a model based on mm size image, the model is in mm
and the simulation parameters should also be in mm?
then cc/s should go mm^3/s and RCR value units should also be in mm^5/dynes and so on?
sorry it seems repeating but I really need confirmation...
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Taehak Kang
- Posts: 39
- Joined: Thu Jun 22, 2017 7:03 pm
Re: CGS and MGS units
I just checked...
the coronary project tutorial image is in mm...
the aorta diameter is 2.86mm from my reading..
the parameters given for the tutorial in the site is in cgs and would the simulation still be right?
the coronary project tutorial image is in mm...
the aorta diameter is 2.86mm from my reading..
the parameters given for the tutorial in the site is in cgs and would the simulation still be right?
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Nathan Wilson
- Posts: 46
- Joined: Tue Jun 20, 2006 9:19 am
Re: CGS and MGS units
Hello Taehak,
It is up to the user to make the units consistent between the solver and the model that was constructed. Almost all image data is in mm, and we typically run most simulations in cm. You can either scale the image volume before you create the model, or create the model in mm and then scale the model to cm before meshing and simulation.
We highly recommend scaling the image volume to cm before you do anything as this tends to make life easier in the long run.
To be very explicit, the unit versions are completely and totally up to the user. Our solver doesn't do any unit conversations whatsoever.
Nathan
SimVascular Developer Team
It is up to the user to make the units consistent between the solver and the model that was constructed. Almost all image data is in mm, and we typically run most simulations in cm. You can either scale the image volume before you create the model, or create the model in mm and then scale the model to cm before meshing and simulation.
We highly recommend scaling the image volume to cm before you do anything as this tends to make life easier in the long run.
To be very explicit, the unit versions are completely and totally up to the user. Our solver doesn't do any unit conversations whatsoever.
Nathan
SimVascular Developer Team
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Taehak Kang
- Posts: 39
- Joined: Thu Jun 22, 2017 7:03 pm
Re: CGS and MGS units
Thank you.. that was not the issue it seems but it worked in the same way as you said in the reply.. Thanks alot for your help and I really owe so much to simvascular developers!