# Discussion Forum

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## How to redeuce memory requirement during comsol simulation

I am new to comsol. I recently built a simple 3D model in comsol.
Oops - it used way much more memory than I expected. I used to build models with
millions of nodes and never had any issues. But now the simulation would crash whenever
the number of elements got close to 1 million. So to all the gurus out there -
what tricks do you know can reduce memory requirement during comsol simulation?

2 Replies Last Post Dec 7, 2012, 2:41 PM EST
Posted: 5 years ago
Hi

3D indeed tend to get very Biiiig and RAM consuming ;)

a few tricks: cqan you use symmetry, to divide our model in 1/ 1/4 or even 1/8 or more ?, can you use 2D as the variations along one axis is small, or do you have a shape very looong, so that the section can be reduced to a point, or do you have cylindrical symmetry, then 2D-axi or 1D axi even is much quicker to solve

Once you have solved for 2D-axi or 2D you can map it back to 3D to give 3D views

Note: COMSOL solves always in 3D, but when you select 2D, the formulas are simplified, and the variables are considered per 1 meter in depth (Z) with no gradients along Z, (or 1 meter square in the section Y-Z perpendicular to the line direction X)

Welcome to the real world :)

--
Good luck
Ivar

Posted: 5 years ago

I am also wondering when COMSOL will support GPU during the solution process.
I will at least need hundreds of GB's if I make my 3D model close to reality (subsurface
flow and heat transport with boreholes). Sounds like GPU might be able to get me there,
unless I spend >\$15K to buy a super computer.

G

Hi

3D indeed tend to get very Biiiig and RAM consuming ;)

a few tricks: cqan you use symmetry, to divide our model in 1/ 1/4 or even 1/8 or more ?, can you use 2D as the variations along one axis is small, or do you have a shape very looong, so that the section can be reduced to a point, or do you have cylindrical symmetry, then 2D-axi or 1D axi even is much quicker to solve

Once you have solved for 2D-axi or 2D you can map it back to 3D to give 3D views

Note: COMSOL solves always in 3D, but when you select 2D, the formulas are simplified, and the variables are considered per 1 meter in depth (Z) with no gradients along Z, (or 1 meter square in the section Y-Z perpendicular to the line direction X)

Welcome to the real world :)

--
Good luck
Ivar

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