Hi All,

To neglect gravity effect, materials and liquid densities are considered as zero. I found some cases, where density is considered as -ve/ +ve value. What does negative sign represent? There are total three files where GRAVITY key word is available

For *. mfp GRAVITY

*.msp GRAVITY_CONSTANT

*.num GRAVITY_PROFILE

I am wondering what is the appropriate way to consider Gravity force effect. I followed following steps, but failed. Any idea how can I achieve gravity force effect?

GeoSys-MAT-FP: Fluid Properties ------------------------------------

#FLUID_PROPERTIES

$FLUID_TYPE

LIQUID

$PCS_TYPE

PRESSURE1

$DENSITY

1 1.0e3

$GRAVITY

9.81

$VISCOSITY

1 1.000000e-003

#STOP

GeoSys-MAT-SP: Solid Properties ------------------------------------

#SOLID_PROPERTIES

$DENSITY

1 2.000000e+003

$GRAVITY_CONSTANT

9.81

$ELASTICITY

POISSION 0.4

YOUNGS_MODULUS

1 1.300000e+006

#STOP

GeoSys-NUM: Numerical Parameter ----------------------------------------

#NUMERICS

$PCS_TYPE

RICHARDS_FLOW

$ELE_UPWINDING

0.5

$ELE_MASS_LUMPING

1

$GRAVITY_PROFILE

1

$LINEAR_SOLVER

; method error_tolerance max_iterations theta precond storage

2 2 1.e-010 2000 1.0 100 4

$NON_LINEAR_SOLVER

; method error_tolerance max_iterations relaxation

PICARD 1e-3 25 0.0

; $COUPLING_ITERATIONS

; HM 5 1.0e-6 // The first string is arbitrary

#NUMERICS

$PCS_TYPE

DEFORMATION

$LINEAR_SOLVER

; method error_tolerance max_iterations theta precond storage

2 5 1.e-10 1000 1.0 100 4

$ELE_GAUSS_POINTS

3

#STOP

Regards,

Mohammad

1 Like

hi, usually you don’t need to use any of the GRAVITY keywords. To neglect gravity effects, you can use negative sign for the densities. The densitiy values (absolute one) will still be used in some calculation, e.g. in heat transport. but don’t ask me why it’s like that…

## ···

From: Mohammad Islam nislamce@gmail.com

Sent: 水曜日, 6月 7, 2017 2:46 午前

Subject: [ogs-users] Density and Gravity Force

To: ogs-users ogs-users@googlegroups.com

Hi All,

To neglect gravity effect, materials and liquid densities are considered as zero. I found some cases, where density is considered as -ve/ +ve value. What does negative sign represent? There are total three files where GRAVITY key word is available

For *. mfp GRAVITY

*.msp GRAVITY_CONSTANT

*.num GRAVITY_PROFILE

I am wondering what is the appropriate way to consider Gravity force effect. I followed following steps, but failed. Any idea how can I achieve gravity force effect?

GeoSys-MAT-FP: Fluid Properties ------------------------------------

#FLUID_PROPERTIES

$FLUID_TYPE

LIQUID

$PCS_TYPE

PRESSURE1

$DENSITY

1 1.0e3

$GRAVITY

9.81

$VISCOSITY

1 1.000000e-003

#STOP

GeoSys-MAT-SP: Solid Properties ------------------------------------

#SOLID_PROPERTIES

$DENSITY

```
1 2.000000e+003
```

$GRAVITY_CONSTANT

9.81

$ELASTICITY

```
POISSION 0.4
YOUNGS_MODULUS
1 1.300000e+006
```

#STOP

GeoSys-NUM: Numerical Parameter ----------------------------------------

#NUMERICS

$PCS_TYPE

RICHARDS_FLOW

$ELE_UPWINDING

0.5

$ELE_MASS_LUMPING

1

$GRAVITY_PROFILE

1

$LINEAR_SOLVER

; method error_tolerance max_iterations theta precond storage

2 2 1.e-010 2000 1.0 100 4

$NON_LINEAR_SOLVER

; method error_tolerance max_iterations relaxation

PICARD 1e-3 25 0.0

; $COUPLING_ITERATIONS

; HM 5 1.0e-6 // The first string is arbitrary

#NUMERICS

$PCS_TYPE

DEFORMATION

$LINEAR_SOLVER

; method error_tolerance max_iterations theta precond storage

2 5 1.e-10 1000 1.0 100 4

$ELE_GAUSS_POINTS

3

#STOP

Regards,

Mohammad

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If negative density value is given in msp file, the gravity force effect in deformation analysis is neglected, while absolute value of the solid density data is still used in calculation of the heat capacity related term when heat transport process being coupled. For fluid density values in mfp, they have to be always positive.

## ···

On 06/07/2017 01:31 AM, 渡邉教弘 wrote:

hi, usually you don't need to use any of the GRAVITY keywords. To neglect gravity effects, you can use negative sign for the densities. The densitiy values (absolute one) will still be used in some calculation, e.g. in heat transport. but don't ask me why it's like that...

_____________________________

From: Mohammad Islam <nislamce@gmail.com>

Sent: 水曜日, 6月 7, 2017 2:46 午前

Subject: [ogs-users] Density and Gravity Force

To: ogs-users <ogs-users@googlegroups.com>

Hi All,

To neglect gravity effect, materials and liquid densities are considered as zero. I found some cases, where density is considered as -ve/ +ve value. What does negative sign represent? There are total three files where GRAVITY key word is available

For *. mfp GRAVITY

*.msp GRAVITY_CONSTANT

*.num GRAVITY_PROFILE

I am wondering what is the appropriate way to consider Gravity force effect. I followed following steps, but failed. Any idea how can I achieve gravity force effect?

GeoSys-MAT-FP: Fluid Properties ------------------------------------

#FLUID_PROPERTIES

$FLUID_TYPE

LIQUID

$PCS_TYPE

PRESSURE1

$DENSITY

1 1.0e3

$GRAVITY

9.81

$VISCOSITY

1 1.000000e-003

#STOP

GeoSys-MAT-SP: Solid Properties ------------------------------------

#SOLID_PROPERTIES

$DENSITY

1 2.000000e+003

$GRAVITY_CONSTANT

9.81

$ELASTICITY

POISSION 0.4

YOUNGS_MODULUS

1 1.300000e+006

#STOP

*

GeoSys-NUM: Numerical Parameter ----------------------------------------

#NUMERICS

$PCS_TYPE

RICHARDS_FLOW

$ELE_UPWINDING

0.5

$ELE_MASS_LUMPING

1

$GRAVITY_PROFILE

1

$LINEAR_SOLVER

; method error_tolerance max_iterations theta precond storage

2 2 1.e-010 2000 1.0 100 4

$NON_LINEAR_SOLVER

; method error_tolerance max_iterations relaxation

PICARD 1e-3 25 0.0

; $COUPLING_ITERATIONS

; HM 5 1.0e-6 // The first string is arbitrary

#NUMERICS

$PCS_TYPE

DEFORMATION

$LINEAR_SOLVER

; method error_tolerance max_iterations theta precond storage

2 5 1.e-10 1000 1.0 100 4

$ELE_GAUSS_POINTS

3

#STOP

Regards,

Mohammad

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Hi,

Thank you for your kind reply.

Regards,

Mohammad

## ···

On Tuesday, 6 June 2017 19:31:49 UTC-4, 渡邉教弘 wrote:

hi, usually you don’t need to use any of the GRAVITY keywords. To neglect gravity effects, you can use negative sign for the densities. The densitiy values (absolute one) will still be used in some calculation, e.g. in heat transport. but don’t ask me why it’s like that…

From: Mohammad Islam nisl...@gmail.com

Sent: 水曜日, 6月 7, 2017 2:46 午前

Subject: [ogs-users] Density and Gravity Force

To: ogs-users ogs-...@googlegroups.com

Hi All,

To neglect gravity effect, materials and liquid densities are considered as zero. I found some cases, where density is considered as -ve/ +ve value. What does negative sign represent? There are total three files where GRAVITY key word is available

For *. mfp GRAVITY

*.msp GRAVITY_CONSTANT

*.num GRAVITY_PROFILE

I am wondering what is the appropriate way to consider Gravity force effect. I followed following steps, but failed. Any idea how can I achieve gravity force effect?

GeoSys-MAT-FP: Fluid Properties ------------------------------------

#FLUID_PROPERTIES

$FLUID_TYPE

LIQUID

$PCS_TYPE

PRESSURE1

$DENSITY

1 1.0e3

$GRAVITY

9.81

$VISCOSITY

1 1.000000e-003

#STOP

GeoSys-MAT-SP: Solid Properties ------------------------------------

#SOLID_PROPERTIES

$DENSITY

```
1 2.000000e+003
```

$GRAVITY_CONSTANT

9.81

$ELASTICITY

```
POISSION 0.4
YOUNGS_MODULUS
1 1.300000e+006
```

#STOP

GeoSys-NUM: Numerical Parameter ----------------------------------------

#NUMERICS

$PCS_TYPE

RICHARDS_FLOW

$ELE_UPWINDING

0.5

$ELE_MASS_LUMPING

1

$GRAVITY_PROFILE

1

$LINEAR_SOLVER

; method error_tolerance max_iterations theta precond storage

2 2 1.e-010 2000 1.0 100 4

$NON_LINEAR_SOLVER

; method error_tolerance max_iterations relaxation

PICARD 1e-3 25 0.0

; $COUPLING_ITERATIONS

; HM 5 1.0e-6 // The first string is arbitrary

#NUMERICS

$PCS_TYPE

DEFORMATION

$LINEAR_SOLVER

; method error_tolerance max_iterations theta precond storage

2 5 1.e-10 1000 1.0 100 4

$ELE_GAUSS_POINTS

3

#STOP

Regards,

Mohammad

–

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Dear Wang,

Thanks again for your help.

Regards,

Mohammad

## ···

On Thursday, 8 June 2017 03:46:25 UTC-4, Wenqing Wang wrote:

```
If negative density value is given in msp file, the gravity force effect in deformation analysis is neglected, while absolute value of the solid density data is still used in calculation of the heat capacity related term when heat transport process being coupled. For fluid density values in mfp, they have to be always positive.
On 06/07/2017 01:31 AM, 渡邉教弘 wrote:
```

```
hi, usually you don't need to use any of the GRAVITY keywords. To neglect gravity effects, you can use negative sign for the densities. The densitiy values (absolute one) will still be used in some calculation, e.g. in heat transport. but don't ask me why it's like that...
```

This conversation is a bit hilarious but very useful in a random way. Thanks, guys. It helps eventually.

Chan-Hee

## ···

On Saturday, June 10, 2017 at 2:57:17 AM UTC+9, Mohammad Islam wrote:

Dear Wang,

Thanks again for your help.

Regards,

Mohammad

On Thursday, 8 June 2017 03:46:25 UTC-4, Wenqing Wang wrote:

```
If negative density value is given in msp file, the gravity force effect in deformation analysis is neglected, while absolute value of the solid density data is still used in calculation of the heat capacity related term when heat transport process being coupled. For fluid density values in mfp, they have to be always positive.
On 06/07/2017 01:31 AM, 渡邉教弘 wrote:
```

```
hi, usually you don't need to use any of the GRAVITY keywords. To neglect gravity effects, you can use negative sign for the densities. The densitiy values (absolute one) will still be used in some calculation, e.g. in heat transport. but don't ask me why it's like that...
```