how to fix the memory allocation error

Mudassir khan
Mudassir khan Altair Community Member
edited September 2022 in Community Q&A

Hello Experts

I am working on hyperwork CFD 2022.1 with dambreak type of simulation. I have developed my model with 70841585 volume mesh elements on my machine having 16GB ram. When I started the simulation after certain time it terminate with memory allocation error or error occur to launch acuprep. Should I need to increase my mesh size to reduce the number of element?. Currently i am using 9 mm size volume mesh element. will it affect my result? what should be the best way to tackle this issue without compromising the accuracy? These are last comments from log file

acuprep: Minimum coordinates = -9.0684e-01 4.0263e+00 5.9431e+00

acuPrep: Maximum coordinates = 8.2390e+00 6.4855e+00 6.1941e+00

acuPrep: Total nodes = 12147394

acuPrep: Total elements = 70841585

acuPrep: Element aggl. = 1

acuPrep: Total aggl. rad. surfaces = 0

acuPrep: Total interface surfaces = 0

acuPrep: *** ASSERTION in Function <memAlloc> File <mem.c> Line <149>

acuPrep: *** Memory Allocation Error

acuPrep: *** Allocated <11758.167969> Mbytes

acuPrep: *** Unable to allocate <2738.945580> Mbytes

acuPrep: RAM space = 734 Mbytes

acuPrep: Swap space = 32272 Mbytes

acuPrep: *** Memory Allocation Error; from file <util.c> line <114>

acuRun: *** ERROR: error occurred executing acuPrep

acuRun: Wed Sep 14 18:27:24 202

 

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Answers

  • acupro
    acupro
    Altair Employee
    edited September 2022

    The base recommendation for memory (RAM) is 3 KB per meshed node - or 3 GB per Million nodes.  Your model has on the order of 12 Million nodes, so you might expect to need on the order of 36 GB RAM.  (There is some dependence on which equations are being solved, etc, but that's a rough idea.)

    It may be easiest to add RAM - at least to 32 GB?  Otherwise you'll need reduce the model mesh count by increasing the element size.  Yes - there will most likely be some effect on the accuracy - but you would need to run the solution with several different mesh sizes to see by how much.

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