Hydrostatic condition for H2M case

Hi All,

I discussed before regarding the hydrostatic equilibrium condition for H2 case. I would like to thank Nori and Wang.

Now I have a situation. I am checking mechanical equilibrium condition and hydrostatic equilibrium condition for H2M case considering CAM_CLAY. Soil column height is 1 m and width 0.1 m. Gravity activated for both Liquid (Density =1000 ) and Solid (Density = 2000) mass. The mechanical equilibrium is working fine, and logical. But, for Hydrostatic condition, in H2 phase, Liquid pressure is triangular and logical. To achieve it, I used

#INITIAL_CONDITION

$PCS_TYPE

MULTI_PHASE_FLOW

$PRIMARY_VARIABLE

PRESSURE1

$GEO_TYPE

DOMAIN

$DIS_TYPE

CONSTANT 0

#INITIAL_CONDITION

$PCS_TYPE

MULTI_PHASE_FLOW

$PRIMARY_VARIABLE

PRESSURE2

$GEO_TYPE

DOMAIN

$DIS_TYPE

GRADIENT 1 0 9810

Now for DEFORMATION, I used as follows

#INITIAL_CONDITION

$PCS_TYPE

DEFORMATION

$PRIMARY_VARIABLE

STRESS_YY

$GEO_TYPE

DOMAIN

$DIS_TYPE

GRADIENT 1 0 19620

At time step zero, STRESS_YY is showing zero, and GRADIENT is not working. But, I need STRESS_YY=Densitygy=20009.81y, at top it need to be zero and bottom 19620. Any idea how to resolve it?

Regards,

Mohammad

Hi,

I think you need to change $PRIMARY_VARIABLE to DISPLACEMENT_Y (or Y1, not sure).

n

···

On 06/15/2017 05:37 AM, Mohammad Islam wrote:

Hi All,
I discussed before regarding the hydrostatic equilibrium condition for H2 case. I would like to thank Nori and Wang.

Now I have a situation. I am checking mechanical equilibrium condition and hydrostatic equilibrium condition for H2M case considering CAM_CLAY. Soil column height is 1 m and width 0.1 m. Gravity activated for both Liquid (Density =1000 ) and Solid (Density = 2000) mass. The mechanical equilibrium is working fine, and logical. But, for Hydrostatic condition, in H2 phase, Liquid pressure is triangular and logical. To achieve it, I used

#INITIAL_CONDITION
        $PCS_TYPE
             MULTI_PHASE_FLOW
       $PRIMARY_VARIABLE
            PRESSURE1
       $GEO_TYPE
           DOMAIN
       $DIS_TYPE
           CONSTANT 0
#INITIAL_CONDITION
        $PCS_TYPE
             MULTI_PHASE_FLOW
       $PRIMARY_VARIABLE
            PRESSURE2
       $GEO_TYPE
           DOMAIN
       $DIS_TYPE
           GRADIENT 1 0 9810

Now for DEFORMATION, I used as follows

#INITIAL_CONDITION
        $PCS_TYPE
             DEFORMATION
       $PRIMARY_VARIABLE
            STRESS_YY
       $GEO_TYPE
           DOMAIN
       $DIS_TYPE
           GRADIENT 1 0 19620

At time step zero, STRESS_YY is showing zero, and GRADIENT is not working. But, I need STRESS_YY=Density*g*y=2000*9.81*y, at top it need to be zero and bottom 19620. Any idea how to resolve it?

Regards,
Mohammad

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Dear Nori,

In Hydrostatic condition, at time=0, Displacements in X, Y, Z directions are zero and OGS results also agree with it. If I use following command, it will provide Displacement gradient along Y-direction. But, I need Vertical Stress gradient due to Gravity force ( Y=1, STRESS_YY=0; Y=0,STRESS_YY=Densityg(1-Y)=19620 )

#INITIAL_CONDITION

$PCS_TYPE

DEFORMATION

$PRIMARY_VARIABLE

DISPLACEMENT_Y

$GEO_TYPE

DOMAIN

$DIS_TYPE

GRADIENT 1 0 19620

I looks GRADIENT command is working fine for H2 case, but some how it is not working for me in Mechanical case, like for DISPLACEMENT_Y or STRESS_YY. Any idea?

Regards,

Mohammad

Regards,

Mohammad

···

On Wednesday, 14 June 2017 17:23:48 UTC-4, Norihiro Watanabe wrote:

Hi,

I think you need to change $PRIMARY_VARIABLE to DISPLACEMENT_Y (or Y1,
not sure).

n

okay.. I thought one should use DISPLACEMENT_Y for stress yy. maybe I'm confused with something else.

how about the following setting?

#INITIAL_CONDITION
  $PCS_TYPE
   DEFORMATION
  $PRIMARY_VARIABLE
   STRESS_YY
  $GEO_TYPE
   SUB_DOMAIN
   1
   0 0+19620*y

···

On 06/15/2017 07:01 AM, Mohammad Islam wrote:

Dear Nori,
In Hydrostatic condition, at time=0, Displacements in X, Y, Z directions are zero and OGS results also agree with it. If I use following command, it will provide Displacement gradient along Y-direction. But, I need Vertical Stress gradient due to Gravity force ( Y=1, STRESS_YY=0; Y=0,STRESS_YY=Density*g*(1-Y)=19620 )
#INITIAL_CONDITION
        $PCS_TYPE
             DEFORMATION
       $PRIMARY_VARIABLE
            DISPLACEMENT_Y
       $GEO_TYPE
           DOMAIN
       $DIS_TYPE
           GRADIENT 1 0 19620

I looks GRADIENT command is working fine for H2 case, but some how it is not working for me in Mechanical case, like for DISPLACEMENT_Y or STRESS_YY. Any idea?

Regards,
Mohammad

Regards,
Mohammad

On Wednesday, 14 June 2017 17:23:48 UTC-4, Norihiro Watanabe wrote:

    Hi,

    I think you need to change $PRIMARY_VARIABLE to DISPLACEMENT_Y (or Y1,
    not sure).

    n

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Dear Nori,
Now it shows some results! Good sign.

But, in bottom 9.475386710584e+001 and top 1.961106694675e+004, while I need at bottom 19620, top 0.Somehow I need to reverse the result.

Regards,

Mohammad

···

On Wednesday, 14 June 2017 18:07:12 UTC-4, Norihiro Watanabe wrote:

okay… I thought one should use DISPLACEMENT_Y for stress yy. maybe I’m
confused with something else.

how about the following setting?

#INITIAL_CONDITION
$PCS_TYPE
DEFORMATION
$PRIMARY_VARIABLE
STRESS_YY
$GEO_TYPE
SUB_DOMAIN
1
0 0+19620*y

On 06/15/2017 07:01 AM, Mohammad Islam wrote:

Dear Nori,
In Hydrostatic condition, at time=0, Displacements in X, Y, Z
directions are zero and OGS results also agree with it. If I use
following command, it will provide Displacement gradient along
Y-direction. But, I need Vertical Stress gradient due to Gravity force (
Y=1, STRESS_YY=0; Y=0,STRESS_YY=Densityg(1-Y)=19620 )
#INITIAL_CONDITION
$PCS_TYPE
DEFORMATION
$PRIMARY_VARIABLE
DISPLACEMENT_Y
$GEO_TYPE
DOMAIN
$DIS_TYPE
GRADIENT 1 0 19620

I looks GRADIENT command is working fine for H2 case, but some how it is
not working for me in Mechanical case, like for DISPLACEMENT_Y or
STRESS_YY. Any idea?

Regards,
Mohammad

Regards,
Mohammad

On Wednesday, 14 June 2017 17:23:48 UTC-4, Norihiro Watanabe wrote:

Hi,

I think you need to change $PRIMARY_VARIABLE to DISPLACEMENT_Y (or Y1,
not sure).

n


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After using following, bottom 1.952524613289e+004 & top 8.933053249650e+000. I wish I could dig out the source of the 8.93 !!

#INITIAL_CONDITION

$PCS_TYPE

DEFORMATION

$PRIMARY_VARIABLE

STRESS_YY

$GEO_TYPE

SUB_DOMAIN

1

0 19620±19620*y

If the value is at a mesh node, 8.93 is probably a result of extrapolation. In OGS, stress used for calculation is stored at Gauss integration points (inside of elements). For output purposes, they are extrapolated to nodal values.

n

···

On 06/15/2017 12:17 PM, Mohammad Islam wrote:

After using following, bottom 1.952524613289e+004 & top 8.933053249650e+000. I wish I could dig out the source of the 8.93 !!

#INITIAL_CONDITION
   $PCS_TYPE
    DEFORMATION
   $PRIMARY_VARIABLE
    STRESS_YY
   $GEO_TYPE
    SUB_DOMAIN
    1
    0 19620+-19620*y

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but please also check if the node coordinate is exactly zero at top.

···

On 06/15/2017 01:01 PM, Norihiro Watanabe wrote:

If the value is at a mesh node, 8.93 is probably a result of extrapolation. In OGS, stress used for calculation is stored at Gauss integration points (inside of elements). For output purposes, they are extrapolated to nodal values.

n

On 06/15/2017 12:17 PM, Mohammad Islam wrote:

After using following, bottom 1.952524613289e+004 & top 8.933053249650e+000. I wish I could dig out the source of the 8.93 !!

#INITIAL_CONDITION
   $PCS_TYPE
    DEFORMATION
   $PRIMARY_VARIABLE
    STRESS_YY
   $GEO_TYPE
    SUB_DOMAIN
    1
    0 19620+-19620*y

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